Integrated processes and systems for conversion of methane to multiple higher hydrocarbon products

ABSTRACT

Integrated systems are provided for the production of higher hydrocarbon compositions, for example liquid hydrocarbon compositions, from methane using an oxidative coupling of methane system to convert methane to ethylene, followed by conversion of ethylene to selectable higher hydrocarbon products. Integrated systems and processes are provided that process methane through to these higher hydrocarbon products.

CROSS-REFERENCE

This application claims the benefit of U.S. Provisional Application No.61/734,865, filed on Dec. 7, 2012, which is incorporated herein byreference in its entirety.

BACKGROUND

Technical Field

This invention is generally related to novel hydrocarbon processes andsystems for the conversion of methane into various higher hydrocarbons.

Description of the Related Art

The chemicals and fuels industry has evolved and developed over timebased upon the relative abundance and highly cost effective productionand refining of crude oil. In particular, inexpensive crude oil andhistorically proven refining technologies have produced large numbers ofhigh value chemicals and chemical precursors that are used in virtuallyevery aspect of human society, from building materials, consumerproducts, automobiles, packaging, sheeting, fabrics, etc. Likewise,crude oil and its refined products are used extensively as fuels andfuel blendstocks for driving cars, trains, boats and airplanes, etc.Despite the historical economics of crude oil refining, geo-politicaland geo-economic forces have tended to impact the availability and costof crude oil. In addition, the expense of recovering oil and itsrelative decrease in abundance has increased its cost over time.

Natural gas, on the other hand, is generally relatively abundant, andparticularly abundant in relatively stable regions, e.g., North America,Eastern Europe and China. However, natural gas suffers from difficultiesassociated with moving high volumes of gas across vast expanses,requiring substantial infrastructure costs, e.g., to build and managecomplex pipelines. Likewise, to date, technologies for the production ofthe aforementioned chemicals and fuels from natural gas have not provento be economical under normal market conditions. It is thereforedesirable to provide processes and systems that can start with naturalgas, and particularly methane in natural gas, for the production ofhigher hydrocarbon materials, and particularly easily transportableliquid compositions, for use as chemicals, chemical precursors, liquidfuels and fuel blendstocks, and the like. The present invention meetsthese and other related needs.

BRIEF SUMMARY

The present invention is generally directed to the production of highvalue olefinic and other hydrocarbon products from abundant feedmaterials, such as methane in natural gas. In particular, the inventionprovides, in certain aspects, integrated and selectable processes andsystems for the production of a wide range of different liquidhydrocarbon compositions from methane, which products can be used inchemical processes, or as fuels or fuel blends.

Embodiments of the invention generally provide integrated systems andprocesses for the conversion of methane to ethylene and subsequentconversion of ethylene to one or more different higher hydrocarbonproducts, and particularly liquid hydrocarbon products.

In one embodiment, the invention provides a method of producing aplurality of hydrocarbon products, the method comprising:

introducing methane and a source of oxidant into an OCM reactor systemcapable of converting methane to ethylene at reactor inlet temperaturesof between about 450° C. and 600° C. and reactor pressures of betweenabout 15 psig and 125 psig, with C2+ selectivity of at least 50%, underconditions for the conversion of methane to ethylene;

converting methane to a product gas comprising ethylene;

introducing separate portions of the product gas into at least first andsecond integrated ethylene conversion reaction systems, each integratedethylene conversion reaction system being configured for convertingethylene into a different higher hydrocarbon product; and

converting the ethylene into different higher hydrocarbon products.

In still other embodiments, the invention provides a method of producinga plurality of liquid hydrocarbon products, the method comprising:

converting methane to a product gas comprising ethylene using acatalytic reactor process; and

contacting separate portions of the product gas with at least twodiscrete catalytic reaction systems selected from linear alpha olefin(LAO) systems, linear olefin systems, branched olefin systems, saturatedlinear hydrocarbon systems, branched hydrocarbon systems, saturatedcyclic hydrocarbon systems, olefinic cyclic hydrocarbon systems,aromatic hydrocarbon systems, oxygenated hydrocarbon systems,halogenated hydrocarbon systems, alkylated aromatic systems, andhydrocarbon polymer systems.

Other embodiments of the present disclosure are directed to a processingsystem, the processing system comprising:

an OCM reactor system comprising an OCM catalyst, the OCM reactor systembeing fluidly connected at an input, to a source of methane and a sourceof oxidant;

at least first and second catalytic ethylene conversion reactor systems,the first catalytic ethylene reactor system being configured to convertethylene to a first higher hydrocarbon, and the second catalyticethylene reactor system being configured to convert ethylene to a secondhigher hydrocarbon different from the first higher hydrocarbon; and

a selective coupling between the OCM reactor system and the first andsecond catalytic ethylene reactor systems configured to selectivelydirect a portion or all of the product gas to each of the first andsecond catalytic ethylene reactor systems.

These and other aspects of the invention will be apparent upon referenceto the following detailed description. To this end, various referencesare set forth herein which describe in more detail certain backgroundinformation, procedures, reactors and/or catalysts, and are each herebyincorporated by reference in their entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, the sizes and relative positions of elements in thedrawings are not necessarily drawn to scale. For example, the variouselements and angles are not drawn to scale, and some of these elementsare arbitrarily enlarged and positioned to improve drawing legibility.Further, the particular shapes of the elements as drawn are not intendedto convey any information regarding the actual shape of the particularelements, and have been selected solely for ease of recognition in thedrawings.

FIG. 1 schematically illustrates a general integrated process flow ofthe invention.

FIG. 2 schematically illustrates an integrated OCM system withintegrated separations system.

FIG. 3 schematically illustrates a process flow for conversion ofethylene to higher liquid hydrocarbons for use in, e.g., fuels and fuelblendstocks.

FIG. 4 schematically illustrates a tubular reactor system for use inconjunction with the present invention.

FIG. 5 schematically illustrates an exemplary reactor system thatprovides varied residence times for reactants.

FIG. 6 schematically illustrates an alternate reactor system for varyingresidence times for reactants.

DETAILED DESCRIPTION

I. General

In the following description, certain specific details are set forth inorder to provide a thorough understanding of various embodiments.However, one skilled in the art will understand that the invention maybe practiced without these details. In other instances, well-knownstructures have not been shown or described in detail to avoidunnecessarily obscuring descriptions of the embodiments. Unless thecontext requires otherwise, throughout the specification and claimswhich follow, the word “comprise” and variations thereof, such as,“comprises” and “comprising” are to be construed in an open, inclusivesense, that is, as “including, but not limited to.” Further, headingsprovided herein are for convenience only and do not interpret the scopeor meaning of the claimed invention.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with the embodiment is included in at least oneembodiment. Thus, the appearances of the phrases “in one embodiment” or“in an embodiment” in various places throughout this specification arenot necessarily all referring to the same embodiment. Furthermore, theparticular features, structures, or characteristics may be combined inany suitable manner in one or more embodiments. Also, as used in thisspecification and the appended claims, the singular forms “a,” “an,” and“the” include plural referents unless the content clearly dictatesotherwise. It should also be noted that the term “or” is generallyemployed in its sense including “and/or” unless the content clearlydictates otherwise.

The present invention is generally directed to novel processes andsystems for use in the production of hydrocarbon compositions. Theseprocesses and systems may be characterized in that they derive thehydrocarbon compositions from ethylene that is, in turn, derived frommethane, for example as is present in natural gas. The disclosedprocesses and systems are typically further characterized in that theprocess for conversion of methane to ethylene is integrated with one ormore processes or systems for converting ethylene to one or more higherhydrocarbon products, which, in some embodiments, comprise liquidhydrocarbon compositions. By converting the methane present in naturalgas to a liquid material, one can eliminate one of the key hurdlesinvolved in exploitation of the world's vast natural gas reserves,namely transportation. In particular, exploitation of natural gasresources traditionally has required extensive, and costly pipelineinfrastructures for movement of gas from the wellhead to its ultimatedestination. By converting that gas to a liquid material, moreconventional transportation systems become available, such as truck,rail car, tanker ship, and the like.

In further embodiments, processes and systems of the invention includemultiple (i.e., two or more) ethylene conversion process pathsintegrated into the overall processes or systems, in order to producemultiple different higher hydrocarbon compositions from the singleoriginal methane source. Further advantages are gained by providing theintegration of these multiple conversion processes or systems in aswitchable or selectable architecture whereby a portion or all of theethylene containing product of the methane to ethylene conversion systemis selectively directed to one or more different process paths, forexample two, three, four, five or more different process paths to yieldas many different products. This overall process flow is schematicallyillustrated in FIG. 1. As shown, an oxidative coupling of methane(“OCM”) reactor system 100 is schematically illustrated that includes anOCM reactor train 102 coupled to a OCM product gas separation train 104,such as a cryogenic separation system. The ethylene rich effluent (shownas arrow 106) from the separation train 104 is shown being routed tomultiple different ethylene conversion reactor systems and processes110, e.g., ethylene conversion systems 110 a-110 e, which each producedifferent hydrocarbon products, e.g., products 120 a-120 e.

As noted, the fluid connection between the OCM reactor system 100 andeach of the different ethylene conversion systems 110 a-110 e, is acontrollable and selective connection in some embodiments, e.g., a valveand control system, that can apportion the output of the OCM reactorsystem to one, two, three, four, five or more different ethyleneconversion systems. Valve and piping systems for accomplishing this maytake a variety of different forms, including valves at each pipingjunction, multiport valves, multi-valved manifold assemblies, and thelike.

As used herein, and unless the context dictates otherwise, the followingterms have the meanings as specified below.

“Catalyst” means a substance that alters the rate of a chemicalreaction. A catalyst may either increase the chemical reaction rate(i.e. a “positive catalyst”) or decrease the reaction rate (i.e. a“negative catalyst”). Catalysts participate in a reaction in a cyclicfashion such that the catalyst is cyclically regenerated. “Catalytic”means having the properties of a catalyst.

“Nanowire” means a nanowire structure having at least one diameter onthe order of nanometers (e.g. between about 1 and 100 nanometers) and anaspect ratio greater than 10:1. The “aspect ratio” of a nanowire is theratio of the actual length (L) of the nanowire to the diameter (D) ofthe nanowire. Aspect ratio is expressed as L:D.

“Polycrystalline nanowire” means a nanowire having multiple crystaldomains. Polycrystalline nanowires generally have different morphologies(e.g. bent vs. straight) as compared to the corresponding“single-crystalline” nanowires.

“Effective length” of a nanowire means the shortest distance between thetwo distal ends of a nanowire as measured by transmission electronmicroscopy (TEM) in bright field mode at 5 keV. “Average effectivelength” refers to the average of the effective lengths of individualnanowires within a plurality of nanowires.

“Actual length” of a nanowire means the distance between the two distalends of a nanowire as traced through the backbone of the nanowire asmeasured by TEM in bright field mode at 5 keV. “Average actual length”refers to the average of the actual lengths of individual nanowireswithin a plurality of nanowires.

The “diameter” of a nanowire is measured in an axis perpendicular to theaxis of the nanowire's actual length (i.e. perpendicular to thenanowires backbone). The diameter of a nanowire will vary from narrow towide as measured at different points along the nanowire backbone. Asused herein, the diameter of a nanowire is the most prevalent (i.e. themode) diameter.

The “ratio of effective length to actual length” is determined bydividing the effective length by the actual length. A nanowire having a“bent morphology” will have a ratio of effective length to actual lengthof less than one as described in more detail herein. A straight nanowirewill have a ratio of effective length to actual length equal to one.

“Inorganic” means a substance comprising a metal element or semi-metalelement. In certain embodiments, inorganic refers to a substancecomprising a metal element. An inorganic compound can contain one ormore metals in its elemental state, or more typically, a compound formedby a metal ion (M^(n+), wherein n 1, 2, 3, 4, 5, 6 or 7) and an anion(X^(m−), m is 1, 2, 3 or 4), which balance and neutralize the positivecharges of the metal ion through electrostatic interactions.Non-limiting examples of inorganic compounds include oxides, hydroxides,halides, nitrates, sulfates, carbonates, phosphates, acetates, oxalates,and combinations thereof, of metal elements. Other non-limiting examplesof inorganic compounds include Li₂CO₃, Li₂PO₄, LiOH, Li₂O, LiCl, LiBr,LiI, Li₂C₂O₄, Li₂SO₄, Na₂CO₃, Na₂PO₄, NaOH, Na₂O, NaCl, NaBr, NaI,Na₂C₂O₄, Na₂SO₄, K₂CO₃, K₂PO₄, KOH, K₂O, KCl, KBr, KI, K₂C₂O₄, K₂SO₄,Cs₂CO₃, CsPO₄, CsOH, CS₂O, CsCl, CsBr, CsI, CsC₂O₄, CsSO₄, Be(OH)₂,BeCO₃, BePO₄, BeO, BeCl₂, BeBr₂, BeI₂, BeC₂O₄. BeSO₄, Mg(OH)₂, MgCO₃,MgPO₄, MgO, MgCl₂, MgBr₂, MgI₂, MgC₂O₄. MgSO₄, Ca(OH)₂, CaO, CaCO₃,CaPO₄, CaCl₂, CaBr₂, CaI₂, Ca(OH)₂, CaC₂O₄, CaSO₄, Y₂O₃, Y₂(CO₃)₃,Y₂(PO₄)₃, Y(OH)₃, YCl₃, YBr₃, YI₃, Y₂(C₂O4)₃, Y₂(SO4)₃, Zr(OH)₄,Zr(CO₃)₂, Zr(PO₄)₂, ZrO(OH)₂, ZrO2, ZrCl₄, ZrBr₄, ZrI₄, Zr(C₂O₄)₂,Zr(SO₄)₂, Ti(OH)₄, TiO(OH)₂, Ti(CO₃)₂, Ti(PO₄)₂, TiO2, TiCl₄, TiBr₄,TiI₄, Ti(C₂O₄)₂, Ti(SO₄)₂, BaO, Ba(OH)₂, BaCO₃, BaPO₄, BaCl₂, BaBr₂,BaI₂, BaC₂O₄, BaSO₄, La(OH)₃, La₂(CO₃)₃, La₂(PO₄)₃, La₂O₃, LaCl₃, LaBr₃,LaI₃, La₂(C₂O₄)₃, La₂(SO₄)₃, Ce(OH)₄, Ce(CO₃)₂, Ce(PO₄)₂, CeO₂, Ce₂O₃,CeCl₄, CeBr₄, CeI₄, Ce(C₂O₄)₂, Ce(SO₄)₂, ThO₂, Th(CO₃)₂, Th(PO₄)₂,ThCl₄, ThBr₄, ThI₄, Th(OH)₄, Th(C₂O₄)₂, Th(SO₄)₂, Sr(OH)₂, SrCO₃, SrPO₄,SrO, SrCl₂, SrBr₂, SrI₂, SrC₂O₄, SrSO₄, Sm₂O₃, Sm₂(CO₃)₃, Sm₂(PO₄)₃,SmCl₃, SmBr₃, SmI₃, Sm(OH)₃, Sm₂(CO3)₃, Sm₂(C₂O₃)₃, Sm₂(SO₄)₃,LiCa₂Bi₃O₄Cl₆, Na₂WO₄, K/SrCoO₃, K/Na/SrCoO₃, Li/SrCoO₃, SrCoO₃,molybdenum oxides, molybdenum hydroxides, molybdenum carbonates,molybdenum phosphates, molybdenum chlorides, molybdenum bromides,molybdenum iodides, molybdenum oxalates, molybdenum sulfates, manganeseoxides, manganese chlorides, manganese bromides, manganese iodides,manganese hydroxides, manganese oxalates, manganese sulfates, manganesetungstates, vanadium oxides, vanadium carbonates, vanadium phosphates,vanadium chlorides, vanadium bromides, vanadium iodides, vanadiumhydroxides, vanadium oxalates, vanadium sulfates, tungsten oxides,tungsten carbonates, tungsten phosphates, tungsten chlorides, tungstenbromides, tungsten iodides, tungsten hydroxides, tungsten oxalates,tungsten sulfates, neodymium oxides, neodymium carbonates, neodymiumphosphates, neodymium chlorides, neodymium bromides, neodymium iodides,neodymium hydroxides, neodymium oxalates, neodymium sulfates, europiumoxides, europium carbonates, europium phosphates, europium chlorides,europium bromides, europium iodides, europium hydroxides, europiumoxalates, europium sulfates rhenium oxides, rhenium carbonates, rheniumphosphates, rhenium chlorides, rhenium bromides, rhenium iodides,rhenium hydroxides, rhenium oxalates, rhenium sulfates, chromium oxides,chromium carbonates, chromium phosphates, chromium chlorides, chromiumbromides, chromium iodides, chromium hydroxides, chromium oxalates,chromium sulfates, potassium molybdenum oxides and the like.

“Salt” means a compound comprising negative and positive ions. Salts aregenerally comprised of cations and counter ions. Under appropriateconditions, e.g., the solution also comprises a template, the metal ion(M^(n+)) and the anion (X^(m−)) bind to the template to inducenucleation and growth of a nanowire of M_(m)X_(n) on the template.“Anion precursor” thus is a compound that comprises an anion and acationic counter ion, which allows the anion (X^(m−)) to dissociate fromthe cationic counter ion in a solution. Specific examples of the metalsalt and anion precursors are described in further detail herein.

“Oxide” refers to a metal compound comprising oxygen. Examples of oxidesinclude, but are not limited to, metal oxides (M^(n+)), metal oxyhalides(M_(x)O_(y)X_(z)), metal hydroxyhalides (M_(x)OH_(y)X_(z)), metaloxynitrates (M_(x)O_(y)(NO₃)_(z)), metal phosphates (M_(x)(PO₄)_(y),metal oxycarbonates (M_(x)O_(y)(CO₃)_(z)), metal carbonates(M_(x)(CO₃)_(z)), metal sulfates (M_(x)(SO₄)_(z)), metal oxysulfates(M_(x)O_(y)(SO₄)_(z)), metal phosphates (M_(x)(PO₄)_(z)), metal acetates(M_(x)(CH₃CO₂)_(z)), metal oxalates (M_(x)(C₂O₄)_(z)), metaloxyhydroxides (M_(x)O_(y)(OH)_(z)), metal hydroxides (M_(x)(OH)_(z)),hydrated metal oxides (M_(x)O_(y)).(H₂O)_(z) and the like, wherein X isindependently, at each occurrence, fluoro, chloro, bromo or iodo, and x,y and z are independently numbers from 1 to 100.

“Mixed oxide” or “mixed metal oxide” refers to a compound comprising twoor more oxidized metals and oxygen (i.e., M1_(x)M2_(y)O_(z), wherein M1and M2 are the same or different metal elements, O is oxygen and x, yand z are numbers from 1 to 100). A mixed oxide may comprise metalelements in various oxidation states and may comprise more than one typeof metal element. For example, a mixed oxide of manganese and magnesiumcomprises oxidized forms of magnesium and manganese. Each individualmanganese and magnesium atom may or may not have the same oxidationstate. Mixed oxides comprising 2, 3, 4, 5, 6 or more metal elements canbe represented in an analogous manner. Mixed oxides also includeoxy-hydroxides (e.g., M_(x)O_(y)OH_(z), wherein M is a metal element, Ois oxygen, x, y and z are numbers from 1 to 100 and OH is hydroxy).Mixed oxides may be represented herein as M1-M2, wherein M1 and M2 areeach independently a metal element.

“Crystal domain” means a continuous region over which a substance iscrystalline.

“Single-crystalline nanowires” or “mono-crystalline” means a nanowirehaving a single crystal domain.

“Dopant” or “doping agent” is an impurity added to or incorporatedwithin a catalyst to optimize catalytic performance (e.g. increase ordecrease catalytic activity). As compared to the undoped catalyst, adoped catalyst may increase or decrease the selectivity, conversion,and/or yield of a reaction catalyzed by the catalyst.

“OCM catalyst” refers to a catalyst capable of catalyzing the OCMreaction.

“Group 1” elements include lithium (Li), sodium (Na), potassium (K),rubidium (Rb), cesium (Cs), and francium (Fr).

“Group 2” elements include beryllium (Be), magnesium (Mg), calcium (Ca),strontium (Sr), barium (Ba), and radium (Ra).

“Group 3” elements include scandium (Sc) and yttrium (Y).

“Group 4” elements include titanium (Ti), zirconium (Zr), halfnium (Hf),and rutherfordium (Rf).

“Group 5” elements include vanadium (V), niobium (Nb), tantalum (Ta),and dubnium (Db).

“Group 6” elements include chromium (Cr), molybdenum (Mo), tungsten (W),and seaborgium (Sg).

“Group 7” elements include manganese (Mn), technetium (Tc), rhenium(Re), and bohrium (Bh).

“Group 8” elements include iron (Fe), ruthenium (Ru), osmium (Os), andhassium (Hs).

“Group 9” elements include cobalt (Co), rhodium (Rh), iridium (Ir), andmeitnerium (Mt).

“Group 10” elements include nickel (Ni), palladium (Pd), platinum (Pt)and darmistadium (Ds).

“Group 11” elements include copper (Cu), silver (Ag), gold (Au), androentgenium (Rg).

“Group 12” elements include zinc (Zn), cadmium (Cd), mercury (Hg), andcopernicium (Cn).

“Lanthanides” include lanthanum (La), cerium (Ce), praseodymium (Pr),neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu),gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium(Er), thulium (Tm), yitterbium (Yb), and lutetium (Lu).

“Actinides” include actinium (Ac), thorium (Th), protactinium (Pa),uranium (U), neptunium (Np), plutonium (Pu), americium (Am), curium(Cm), berklelium (Bk), californium (Cf), einsteinium (Es), fermium (Fm),mendelevium (Md), nobelium (No), and lawrencium (Lr).

“Rare earth” elements include Group 3, lanthanides and actinides.

“Metal element” or “metal” is any element, except hydrogen, selectedfrom Groups 1 through 12, lanthanides, actinides, aluminum (Al), gallium(Ga), indium (In), tin (Sn), thallium (Tl), lead (Pb), and bismuth (Bi).Metal elements include metal elements in their elemental form as well asmetal elements in an oxidized or reduced state, for example, when ametal element is combined with other elements in the form of compoundscomprising metal elements. For example, metal elements can be in theform of hydrates, salts, oxides, as well as various polymorphs thereof,and the like.

“Semi-metal element” refers to an element selected from boron (B),silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium(Te), and polonium (Po).

“Non-metal element” refers to an element selected from carbon (C),nitrogen (N), oxygen (O), fluorine (F), phosphorus (P), sulfur (S),chlorine (Cl), selenium (Se), bromine (Br), iodine (I), and astatine(At).

II. Methane to Ethylene Processes and Systems

As noted previously, the present invention includes processes andsystems for production of various higher hydrocarbons (i.e., C3+) fromethylene, and particularly liquid hydrocarbon compositions. Inparticular aspects, the ethylene is itself derived from methane in amethane containing feedstock, such as natural gas. Production ofethylene from methane has been proposed through a number of differentcatalytic pathways, for example in some embodiments, the processes andsystems of the invention convert methane to ethylene through OCM in anOCM reactor system. In certain embodiments, the ethylene produced in theOCM reactor system is charged to one or more ethylene conversion reactorsystems where it is converted to a higher hydrocarbon, for example adifferent higher hydrocarbon in each of the ethylene conversion reactorsystems.

Briefly, the OCM reaction is as follows: 2CH₄+O₂→C₂H₄+2H₂O. See, e.g.,Zhang, Q., Journal of Natural Gas Chem., 12:81, 2003; Olah, G.“Hydrocarbon Chemistry”, Ed. 2, John Wiley & Sons (2003). This reactionis exothermic (ΔH=−67 kcals/mole) and has typically been shown to occurat very high temperatures (>700° C.). Although the detailed reactionmechanism is not fully characterized, experimental evidence suggeststhat free radical chemistry is involved. (Lunsford, J. Chem. Soc., Chem.Comm., 1991; H. Lunsford, Angew. Chem., Int. Ed. Engl., 34:970, 1995).In the reaction, methane (CH₄) is activated on the catalyst surface,forming methyl radicals which then couple in the gas phase to formethane (C₂H₆), followed by dehydrogenation to ethylene (C₂H₄). Severalcatalysts have shown activity for OCM, including various forms of ironoxide, V₂O₅, MoO₃, Co₃O₄, Pt—Rh, Li/ZrO₂, Ag—Au, Au/Co₃O₄, Co/Mn, CeO₂,MgO, La₂O₃, Mn₃O₄, Na₂WO₄, MnO, ZnO, and combinations thereof, onvarious supports. A number of doping elements have also proven to beuseful in combination with the above catalysts.

Since the OCM reaction was first reported over thirty years ago, it hasbeen the target of intense scientific and commercial interest, but thefundamental limitations of the conventional approach to C—H bondactivation appear to limit the yield of this attractive reaction. Inparticular, numerous publications from industrial and academic labs haveconsistently demonstrated characteristic performance of high selectivityat low conversion of methane, or low selectivity at high conversion (J.A. Labinger, Cat. Lett., 1:371, 1988). Limited by thisconversion/selectivity threshold, no OCM catalyst has been able toexceed 20-25% combined C2 yield (i.e. ethane and ethylene), and moreimportantly, only approach these yields when operated at extremely hightemperatures (>800° C.).

Despite the historical limitations of reported OCM processes, newerdevelopments have provided OCM reactions, processes and systems thatoperate within economic and reasonable process windows. In particular,new catalysts, processes and reactor systems have been able to carry outOCM reactions at temperatures, pressures, selectivities and yields thatare commercially attractive, and far more feasible from a processstandpoint than previously reported reactions. See, e.g., U.S. patentapplication Ser. Nos. 13/115,082, 13/479,767, 13/689,611, 13/739,954,13/900,898, 13/901,319, 61/773,669, 61/794,486, 61/909,840 and61/669,523, the full disclosures of which are incorporated herein byreference in their entirety for all purposes.

As used herein, an OCM process or system typically employs one or morereactor vessels that contain an appropriate OCM catalyst material,typically in conjunction with additional system components. A variety ofOCM catalysts have been described previously. See, e.g., U.S. Pat. Nos.5,712,217, 6,403,523, and 6,576,803, the full disclosures of which areincorporated herein by reference in their entirety for all purposes.While these catalysts have been shown to catalyze an OCM reaction, formost of these catalysts, the reactions are carried out under conditionsthat are less practical or economical, i.e., at very high temperaturesand/or pressures. Recently, novel catalysts have been developed thatyield conversion and selectivity that enable economic methane conversionunder practical operating conditions. These are described in, forexample, Published U.S. Patent Application No. 2012-0041246, as well aspatent application Ser. No. 13/479,767, filed May 24, 2012, and Ser. No.13/689,611, filed Nov. 29, 2012, the full disclosures of each of whichare incorporated herein by reference in their entirety for all purposes.

Accordingly, in one embodiment, the invention provides a method ofproducing a hydrocarbon product, the method comprising:

introducing methane and a source of oxidant into an OCM reactor systemcapable of converting methane to ethylene at reactor inlet temperaturesof between about 450° C. and 600° C. and reactor pressures of betweenabout 15 psig and 125 psig, with C2+ selectivity of at least 50%, underconditions for the conversion of methane to ethylene;

converting methane to a product gas comprising ethylene;

introducing at least a portion of the product gas into an integratedethylene conversion reaction systems, the integrated ethylene conversionreaction system being configured for converting ethylene into a higherhydrocarbon product: and

converting the ethylene into a higher hydrocarbon product.

In various embodiments of the above, the method is for producing aplurality of hydrocarbon products. Accordingly, in another embodiment,the invention provides a method of producing a plurality of hydrocarbonproducts, the method comprising:

introducing methane and a source of oxidant into an OCM reactor systemcapable of converting methane to ethylene at reactor inlet temperaturesof between about 450° C. and 600° C. and reactor pressures of betweenabout 15 psig and 125 psig, with C2+ selectivity of at least 50%, underconditions for the conversion of methane to ethylene;

converting methane to a product gas comprising ethylene;

introducing separate portions of the product gas into at least first andsecond integrated ethylene conversion reaction systems, each integratedethylene conversion reaction system being configured for convertingethylene into a different higher hydrocarbon product: and

converting the ethylene into different higher hydrocarbon products.

In certain embodiments of the foregoing methods, the integrated ethyleneconversion systems are selected from selective and full range ethyleneconversion systems.

In other embodiments the methods further comprise introducing a portionof the product gas into at least a third integrated ethylene conversionsystem. Other embodiments further comprise introducing a portion of theproduct gas into at least first, second, third and fourth integratedethylene conversion systems.

In any of the foregoing methods, the integrated ethylene conversionsystems are selected from linear alpha olefin (LAO) systems, linearolefin systems, branched olefin systems, saturated linear hydrocarbonsystems, branched hydrocarbon systems, saturated cyclic hydrocarbonsystems, olefinic cyclic hydrocarbon systems, aromatic hydrocarbonsystems, oxygenated hydrocarbon systems, halogenated hydrocarbonsystems, alkylated aromatic systems, and hydrocarbon polymer systems.

In some other embodiments, the integrated ethylene conversion systemsare selected from LAO systems that produce one or more of 1-butene,1-hexene, 1-octene and 1-decene. For example, in certain embodiments atleast one of the LAO systems is configured for performing a selectiveLAO process.

In other embodiments of the foregoing, at least one of the integratedethylene conversion systems comprises a full range ethyleneoligomerization system configured for producing higher hydrocarbons inthe range of C4 to C30.

In yet other embodiments, the OCM reactor system comprises nanowire OCMcatalyst material. In some other embodiments, the product gas comprisesless than 5 mol % of ethylene. For example, in certain embodiments, theproduct gas comprises less than 3 mol % of ethylene. In some otherembodiments, the product gas further comprises one or more gasesselected from CO₂, CO, H₂, H₂O, C₂H₆, CH₄ and C3+ hydrocarbons.

In other embodiments of the foregoing method, the method furthercomprises enriching the product gas for ethylene prior to introducingthe separate portions of the product gas into the at least first andsecond integrated ethylene conversion reaction systems.

In some different embodiments, the foregoing method further comprisesintroducing an effluent gas from the first or second integrated ethyleneconversion reaction systems into the OCM reactor system. For example, insome of these embodiments the method further comprises convertingmethane present in the effluent gas to ethylene and charging theethylene to one or more of the aforementioned integrated ethyleneconversion systems.

In various different embodiments, the invention is directed to a methodof producing a plurality of hydrocarbon products, the method comprising:

introducing methane and a source of oxidant into an OCM reactor systemcapable of converting methane to ethylene at reactor inlet temperaturesof between about 450° C. and 600° C. and reactor pressures of betweenabout 15 psig and 125 psig, with C2+ selectivity of at least 50%, underconditions for the conversion of methane to ethylene;

recovering ethylene from the OCM reactor system; and

introducing separate portions of the ethylene recovered from the OCMreactor system into at least two integrated, but discrete and differentcatalytic ethylene conversion reaction systems for converting ethyleneinto at least two different higher hydrocarbon products.

In another embodiment of the foregoing method, the at least two ethyleneconversion systems are selected from selective and full range ethyleneconversion systems. In some other embodiments, the at least two ethyleneconversion systems comprise at least three ethylene conversion systems.For example, in some embodiments the at least two ethylene conversionsystems comprise at least four ethylene conversion systems.

In yet more embodiments of the above method, the at least two ethyleneconversion systems are selected from linear alpha olefin (LAO) systems,linear olefin systems, branched olefin systems, saturated linearhydrocarbon systems, branched hydrocarbon systems, saturated cyclichydrocarbon systems, olefinic cyclic hydrocarbon systems, aromatichydrocarbon systems, oxygenated hydrocarbon systems, halogenatedhydrocarbon systems, alkylated aromatic systems, and hydrocarbon polymersystems.

In other aspects, the at least two ethylene conversion systems areselected from LAO systems that produce one or more of 1-butene,1-hexene, 1-octene and 1-decene. For example, in some embodiments atleast one of the at least two LAO processes comprises a selective LAOprocess, and in other exemplary embodiments at least one of the at leasttwo ethylene conversion systems comprises a full range ethyleneoligomerization system for producing higher hydrocarbons in the range ofC4 to C30.

In other specific embodiments, the OCM reactor system comprises nanowireOCM catalyst material.

In different embodiments, the invention provides a method of producing aplurality of liquid hydrocarbon products, comprising:

converting methane to a product gas comprising ethylene using acatalytic reactor process; and

contacting separate portions of the product gas with at least twodiscrete catalytic reaction systems selected from linear alpha olefin(LAO) systems, linear olefin systems, branched olefin systems, saturatedlinear hydrocarbon systems, branched hydrocarbon systems, saturatedcyclic hydrocarbon systems, olefinic cyclic hydrocarbon systems,aromatic hydrocarbon systems, oxygenated hydrocarbon systems,halogenated hydrocarbon systems, alkylated aromatic systems, andhydrocarbon polymer systems.

In still different aspects of the disclosed invention, a method ofproducing a plurality of liquid hydrocarbon products is provided. Themethod comprises:

converting methane to ethylene using a catalytic reactor process;

recovering ethylene from the catalytic reactor process; and

contacting separate portions of the ethylene recovered from the OCMreactor system with at least two discrete catalytic reaction systemsselected from linear alpha olefin (LAO) systems, linear olefin systems,branched olefin systems, saturated linear hydrocarbon systems, branchedhydrocarbon systems, saturated cyclic hydrocarbon systems, olefiniccyclic hydrocarbon systems, aromatic hydrocarbon systems, oxygenatedhydrocarbon systems, halogenated hydrocarbon systems, alkylated aromaticsystems, and hydrocarbon polymer systems.

Other embodiments of the present disclosure are directed to a processingsystem for preparation of C+ hydrocarbon products from methane. Forexample, in some embodiments the invention provides a processing systemcomprising:

an OCM reactor system comprising an OCM catalyst, the OCM reactor systembeing fluidly connected at an input, to a source of methane and a sourceof oxidant;

an integrated ethylene conversion reactor system, the ethylene reactorsystem being configured to convert ethylene to a higher hydrocarbon; and

a selective coupling between the OCM reactor system and the ethylenereactor system, the selective coupling configured to selectively directa portion or all of the product gas to the ethylene conversion reactorsystem.

In variations of the above, the invention provides a processing systemcomprising:

an OCM reactor system comprising an OCM catalyst, the OCM reactor systembeing fluidly connected at an input, to a source of methane and a sourceof oxidant;

at least first and second catalytic ethylene conversion reactor systems,the first catalytic ethylene reactor system being configured to convertethylene to a first higher hydrocarbon, and the second catalyticethylene reactor system being configured to convert ethylene to a secondhigher hydrocarbon different from the first higher hydrocarbon; and

a selective coupling between the OCM reactor system and the first andsecond catalytic ethylene reactor systems configured to selectivelydirect a portion or all of the product gas to each of the first andsecond catalytic ethylene reactor systems.

In some embodiments of the foregoing systems, the ethylene conversionsystems are selected from linear alpha olefin (LAO) systems, linearolefin systems, branched olefin systems, saturated linear hydrocarbonsystems, branched hydrocarbon systems, saturated cyclic hydrocarbonsystems, olefinic cyclic hydrocarbon systems, aromatic hydrocarbonsystems, oxygenated hydrocarbon systems, halogenated hydrocarbonsystems, alkylated aromatic systems, ethylene copolymerization systems,and hydrocarbon polymer systems.

In still other embodiments of the foregoing systems, the OCM catalystcomprises a nanowire catalyst. In more embodiments, the system furthercomprises an ethylene recovery system fluidly coupled between the OCMreactor system and the at least first and second catalytic ethyleneconversion reactor systems, the ethylene recovery system configured forenriching the product gas for ethylene.

In other different embodiments, the invention is directed to aprocessing system, the processing system comprising:

an OCM reactor system comprising an OCM catalyst, the OCM reactor systembeing fluidly connected at an input, to a source of methane and a sourceof oxidant;

an ethylene recovery system fluidly coupled to the OCM reactor system atan outlet, for recovering ethylene from an OCM product gas;

at least first and second catalytic ethylene conversion reactor systems,the first catalytic ethylene reactor system being configured to convertethylene to a first higher hydrocarbon composition, and the secondcatalytic ethylene reactor system being configured to convert ethyleneto a second higher hydrocarbon composition different from the firsthigher hydrocarbon composition; and

a selective coupling between the outlet of the ethylene recovery systemand the first and second catalytic ethylene reactor systems toselectively direct a portion or all of the ethylene recovered from theOCM product gas to each of the first and second catalytic ethylenereactor systems.

In some embodiments of the foregoing processing system, two or more ofthe at least two ethylene conversion systems are selected from linearalpha olefin (LAO) systems, linear olefin systems, branched olefinsystems, saturated linear hydrocarbon systems, branched hydrocarbonsystems, saturated cyclic hydrocarbon systems, olefinic cyclichydrocarbon systems, aromatic hydrocarbon systems, oxygenatedhydrocarbon systems, halogenated hydrocarbon systems, alkylated aromaticsystems, ethylene copolymerization systems, and hydrocarbon polymersystems. In other embodiments, the OCM catalyst comprises a nanowirecatalyst.

In still other embodiments, the catalyst systems used in any of theabove described OCM reaction comprise nanowire catalysts. Such nanowirecatalysts include substantially straight nanowires or nanowires having acurved, twisted or bent morphology. The actual lengths of the nanowirecatalysts may vary. For example in some embodiments, the nanowires havean actual length of between 100 nm and 100 μm. In other embodiments, thenanowires have an actual length of between 100 nm and 10 μm. In otherembodiments, the nanowires have an actual length of between 200 nm and10 μm. In other embodiments, the nanowires have an actual length ofbetween 500 nm and 5 μm. In other embodiments, the actual length isgreater than 5 μm. In other embodiments, the nanowires have an actuallength of between 800 nm and 1000 nm. In other further embodiments, thenanowires have an actual length of 900 nm. As noted below, the actuallength of the nanowires may be determined by TEM, for example, in brightfield mode at 5 keV.

The diameter of the nanowires may be different at different points alongthe nanowire backbone. However, the nanowires comprise a mode diameter(i.e., the most frequently occurring diameter). As used herein, thediameter of a nanowire refers to the mode diameter. In some embodiments,the nanowires have a diameter of between 1 nm and 10 μm, between 1 nmand 1 μm, between 1 nm and 500 nm, between 1 nm and 100 nm, between 7 nmand 100 nm, between 7 nm and 50 nm, between 7 nm and 25 nm, or between 7nm and 15 nm. On other embodiments, the diameter is greater than 500 nm.As noted below, the diameter of the nanowires may be determined by TEM,for example, in bright field mode at 5 keV.

The nanowire catalysts may have different aspect ratios. In someembodiments, the nanowires have an aspect ratio of greater than 10:1. Inother embodiments, the nanowires have an aspect ratio greater than 20:1.In other embodiments, the nanowires have an aspect ratio greater than50:1. In other embodiments, the nanowires have an aspect ratio greaterthan 100:1.

In some embodiments, the nanowires comprise a solid core while in otherembodiments, the nanowires comprise a hollow core. In general, themorphology of a nanowire (including length, diameter, and otherparameters) can be determined by transmission electron microscopy (TEM).Transmission electron microscopy (TEM) is a technique whereby a beam ofelectrons is transmitted through an ultra thin specimen, interactingwith the specimen as it passes through. An image is formed from theinteraction of the electrons transmitted through the specimen. The imageis magnified and focused onto an imaging device, such as a fluorescentscreen, on a layer of photographic film or detected by a sensor such asa CCD camera. TEM techniques are well known to those of skill in theart.

In some embodiments, the nanowire catalysts comprise one or multiplecrystal domains, e.g., monocrystalline or polycrystalline, respectively.In some other embodiments, the average crystal domain of the nanowiresis less than 100 nm, less than 50 nm, less than 30 nm, less than 20 nm,less than 10 nm, less than 5 nm, or less than 2 nm. Crystal structure,composition, and phase, including the crystal domain size of thenanowires, can be determined by XRD.

Typically, the nanowire catalytic material comprises a plurality ofnanowires. In certain embodiments, the plurality of nanowires form amesh of randomly distributed and, to various degrees, interconnectednanowires, that presents a porous matrix.

The total surface area per gram of a nanowire or plurality of nanowiresmay have an effect on the catalytic performance. Pore size distributionmay affect the nanowires catalytic performance as well. Surface area andpore size distribution of the nanowires or plurality of nanowires can bedetermined by BET (Brunauer, Emmett, Teller) measurements. BETtechniques utilize nitrogen adsorption at various temperatures andpartial pressures to determine the surface area and pore sizes ofcatalysts. BET techniques for determining surface area and pore sizedistribution are well known in the art. In some embodiments thenanowires have a surface area of between 0.0001 and 3000 m²/g, between0.0001 and 2000 m²/g, between 0.0001 and 1000 m²/g, between 0.0001 and500 m²/g, between 0.0001 and 100 m²/g, between 0.0001 and 50 m²/g,between 0.0001 and 20 m²/g, between 0.0001 and 10 m²/g or between 0.0001and 5 m²/g. In some embodiments the nanowires have a surface area ofbetween 0.001 and 3000 m²/g, between 0.001 and 2000 m²/g, between 0.001and 1000 m²/g, between 0.001 and 500 m²/g, between 0.001 and 100 m²/g,between 0.001 and 50 m²/g, between 0.001 and 20 m²/g, between 0.001 and10 m²/g or between 0.001 and 5 m²/g. In some other embodiments thenanowires have a surface area of between 2000 and 3000 m²/g, between1000 and 2000 m²/g, between 500 and 1000 m²/g, between 100 and 500 m²/g,between 10 and 100 m²/g, between 5 and 50 m²/g, between 2 and 20 m²/g orbetween 0.0001 and 10 m²/g. In other embodiments, the nanowires have asurface area of greater than 2000 m²/g, greater than 1000 m²/g, greaterthan 500 m²/g, greater than 100 m²/g, greater than 50 m²/g, greater than20 m²/g, greater than 10 m²/g, greater than 5 m²/g, greater than 1 m²/g,greater than 0.0001 m²/g.

The nanowire catalysts and catalyst compositions used in conjunctionwith the processes and systems of some embodiments of the invention mayhave any number of compositions and/or morphologies. These nanowirecatalysts may be inorganic and either polycrystalline ormono-crystalline. In some other embodiments, the nanowires are inorganicand polycrystalline. In certain examples, the nanowire catalystscomprise one or more elements from any of Groups 1 through 7,lanthanides, actinides or combinations thereof. Thus in certain aspects,the catalysts comprise an inorganic catalytic polycrystalline nanowire,the nanowire having a ratio of effective length to actual length of lessthan one and an aspect ratio of greater than ten as measured by TEM inbright field mode at 5 keV, wherein the nanowire comprises one or moreelements from any of Groups 1 through 7, lanthanides, actinides orcombinations thereof.

In still other cases, the nanowire catalysts comprise one or more metalelements from any of Groups 1-7, lanthanides, actinides or combinationsthereof, for example, the nanowires may be mono-metallic, bi-metallic,tri-metallic, etc. (i.e., contain one, two, three, etc. metal elements),where the metal elements may be present in the nanowires in elemental oroxidized form, or in the form of a compound comprising a metal element.The metal element or compound comprising the metal element may be in theform of oxides, hydroxides, oxyhydroxides, salts, hydrated oxides,carbonates, oxy-carbonates, sulfates, phosphates, acetates, oxalates andthe like. The metal element or compound comprising the metal element mayalso be in the form of any of a number of different polymorphs orcrystal structures.

In certain examples, metal oxides may be hygroscopic and may changeforms once exposed to air, may absorb carbon dioxide, may be subjectedto incomplete calcination or any combination thereof. Accordingly,although the nanowires are often referred to as metal oxides, in certainembodiments the nanowires also comprise hydrated oxides, oxyhydroxides,hydroxides, oxycarbonates (or oxide carbonates), carbonates orcombinations thereof.

In many cases, the nanowires comprise one or more metal elements fromGroup 1, Group 2, Group 3, Group 4, Group 5, Group 6, Group 7,lanthanides, and/or actinides, or combinations of these, as well asoxides of these metals. In other cases, the nanowires comprisehydroxides, sulfates, carbonates, oxide carbonates, acetates, oxalates,phosphates (including hydrogen phosphates and dihydrogenphosphates),oxy-carbonates, oxyhalides, hydroxyhalides, oxyhydroxides, oxysulfates,mixed oxides or combinations thereof of one or more metal elements fromany of Groups 1-7, lanthanides, actinides or combinations thereof.Examples of such nanowire materials include, but are not limited tonanowires comprising, e.g., Li₂CO₃, LiOH, Li₂O, Li₂C₂O₄, Li₂SO₄, Na₂CO₃,NaOH, Na₂O, Na₂C₂O₄, Na₂SO₄, K₂CO₃, KOH, K₂O, K₂C₂O₄, K₂SO₄, Cs₂CO₃,CsOH, Cs₂O, CsC₂O₄, CsSO₄, Be(OH)₂, BeCO₃, BeO, BeC₂O₄. BeSO₄, Mg(OH)₂,MgCO₃, MgO, MgC₂O₄. MgSO₄, Ca(OH)₂, CaO, CaCO₃, CaC₂O₄, CaSO₄, Y₂O₃,Y₂(CO₃)₃, Y(OH)₃, Y₂(C₂O4)₃, Y₂(SO₄)₃, Zr(OH)₄, ZrO(OH)₂, ZrO2,Zr(C₂O₄)₂, Zr(SO₄)₂, Ti(OH)₄, TiO(OH)₂, TiO₂, Ti(C₂O₄)₂, Ti(SO₄)₂, BaO,Ba(OH)₂, BaCO₃, BaC₂O₄, BaSO₄, La(OH)₃, La₂O₃, La₂(C₂O₄)₃, La₂(SO₄)₃,La₂(CO₃)₃, Ce(OH)₄, CeO₂, Ce₂O₃, Ce(C₂O₄)₂, Ce(SO₄)₂, Ce(CO₃)₂, ThO₂,Th(OH)₄, Th(C₂O₄)₂, Th(SO₄)₂, Th(CO₃)₂, Sr(OH)₂, SrCO₃, SrO, SrC₂O₄,SrSO₄, Sm₂O₃, Sm(OH)₃, Sm₂(CO₃)₃, Sm₂(C₂O₄)₃, Sm₂(SO₄)₃, LiCa₂Bi₃O₄Cl₆,NaMnO₄, Na₂WO₄, NaMn/WO₄, CoWO₄, CuWO₄, K/SrCoO₃, K/Na/SrCoO₃,Na/SrCoO₃, Li/SrCoO₃, SrCoO₃, Mg₆MnO₈, LiMn₂O₄, Li/Mg₆MnO₈,Na₁₀Mn/W₅O₁₇, Mg₃Mn₃B₂O₁₀, Mg₃(BO₃)₂, molybdenum oxides, molybdenumhydroxides, molybdenum oxalates, molybdenum sulfates, Mn₂O₃, Mn₃O₄,manganese oxides, manganese hydroxides, manganese oxalates, manganesesulfates, manganese tungstates, manganese carbonates, vanadium oxides,vanadium hydroxides, vanadium oxalates, vanadium sulfates, tungstenoxides, tungsten hydroxides, tungsten oxalates, tungsten sulfates,neodymium oxides, neodymium hydroxides, neodymium carbonates, neodymiumoxalates, neodymium sulfates, europium oxides, europium hydroxides,europium carbonates, europium oxalates, europium sulfates, praseodymiumoxides, praseodymium hydroxides, praseodymium carbonates, praseodymiumoxalates, praseodymium sulfates, rhenium oxides, rhenium hydroxides,rhenium oxalates, rhenium sulfates, chromium oxides, chromiumhydroxides, chromium oxalates, chromium sulfates, potassium molybdenumoxides/silicon oxide or combinations thereof.

Still other examples of these nanowire materials include, but are notlimited to, nanowires comprising, e.g., Li₂O, Na₂O, K₂O, Cs₂O, BeO MgO,CaO, ZrO(OH)₂, ZrO₂, TiO₂, TiO(OH)₂, BaO, Y₂O₃, La₂O₃, CeO₂, Ce₂O3,ThO₂, SrO, Sm₂O₃, Nd₂O₃, Eu₂O₃, Pr₂O₃, LiCa₂Bi₃O₄C₁₆, NaMnO₄, Na₂WO₄,Na/Mn/WO₄, Na/MnWO₄, Mn/WO₄, K/SrCoO₃, K/Na/SrCoO₃, K/SrCoO₃, Na/SrCoO₃,Li/SrCoO₃, SrCoO₃, Mg₆MnO₈, Na/B/Mg₆MnO₈, Li/B/Mg₆MnO₈, Zr₂Mo₂O₈,molybdenum oxides, Mn₂O₃, Mn₃O₄, manganese oxides, vanadium oxides,tungsten oxides, neodymium oxides, rhenium oxides, chromium oxides, orcombinations thereof. A variety of different nanowire compositions havebeen described in, e.g., Published U.S. Patent Application No.2012-0041246 and U.S. patent application Ser. No. 13/689,611, filed Nov.29, 2012 (the full disclosures of which are incorporated herein in theirentirety for all purposes), and are envisioned for use in conjunctionwith the present invention.

Products produced from these catalytic reactions typically include CO,CO₂, H₂0, C2+ hydrocarbons, such as ethylene, ethane, and larger alkanesand alkenes, such as propane and propylene. In some embodiments, the OCMreactor systems operate to convert methane into desired higherhydrocarbon products (ethane, ethylene, propane, propylene, butanes,pentanes, etc.), collectively referred to as C2+ compounds, with highyield. In particular, the progress of the OCM reaction is generallydiscussed in terms of methane conversion, C2+ selectivity, and C2+yield. As used herein, methane conversion generally refers to thepercentage or fraction of methane introduced into the reaction that isconverted to a product other than methane. C2+ selectivity generallyrefers to the percentage of all non-methane, carbon containing productsof the OCM reaction that are the desired C2+ products, e.g., ethane,ethylene, propane, propylene, etc. Although primarily stated as C2+selectivity, it will be appreciated that selectivity may be stated interms of any of the desired products, e.g., just C2, or just C2 and C3.Finally, C2+ yield generally refers to the amount of carbon that isincorporated into a C2+ product as a percentage of the amount of carbonintroduced into a reactor in the form of methane. This may generally becalculated as the product of the conversion and the selectivity dividedby the number of carbon atoms in the desired product. C2+ yield istypically additive of the yield of the different C2+ components includedin the C2+ components identified, e.g., ethane yield+ethyleneyield+propane yield+propylene yield etc.).

Exemplary OCM processes and systems typically provide a methaneconversion of at least 10% per process pass in a single integratedreactor system (e.g., single isothermal reactor system or integratedmultistage adiabatic reactor system), with a C2+ selectivity of at least50%, but at reactor inlet temperatures of between 400 and 600° C. and atreactor inlet pressures of between about 15 psig and about 150 psig.Thus, the catalysts employed within these reactor systems are capable ofproviding the described conversion and selectivity under the describedreactor conditions of temperature and pressure. In the context of someOCM catalysts and system embodiments, it will be appreciated that thereactor inlet or feed temperatures typically substantially correspond tothe minimum “light-off” or reaction initiation temperature for thecatalyst or system. Restated, the feed gases are contacted with thecatalyst at a temperature at which the OCM reaction is able to beinitiated upon introduction to the reactor. Because the OCM reaction isexothermic, once light-off is achieved, the heat of the reaction wouldbe expected to maintain the reaction at suitable catalytic temperatures,and even generate excess heat.

In certain aspects, the OCM reactors and reactor systems, when carryingout the OCM reaction, operate at pressures of between about 15 psig andabout 125 psig at the above described temperatures, while providing theconversion and selectivity described above, and in even moreembodiments, at pressures less than 100 psig, e.g., between about 15psig and about 100 psig.

Examples of particularly useful catalyst materials are described in, forexample, Published U.S. Patent Application No. 2012-0041246, as well aspatent application Ser. No. 13/479,767, filed May 24, 2012, and Ser. No.13/689,611, filed Nov. 29, 2012, previously incorporated herein byreference in their entirety for all purposes. In some embodiments, thecatalysts comprise bulk catalyst materials, e.g., having relativelyundefined morphology or, in certain embodiments, the catalyst materialcomprises, at least in part, nanowire containing catalytic materials. Ineither form, the catalysts used in accordance with the present inventionmay be employed under the full range of reaction conditions describedabove, or in any narrower described range of conditions. Similarly, thecatalyst materials may be provided in a range of different larger scaleforms and formulations, e.g., as mixtures of materials having differentcatalytic activities, mixtures of catalysts and relatively inert ordiluent materials, incorporated into extrudates, pellets, or monolithicforms, or the like. Ranges of exemplary catalyst forms and formulationsare described in, for example, U.S. patent application Ser. No.13/901,319 and 61/909,840, the full disclosures of which areincorporated herein by reference in their entireties for all purposes.

The reactor vessels used for carrying out the OCM reaction in the OCMreactor systems of the invention may include one or more discretereactor vessels each containing OCM catalyst material, fluidly coupledto a methane source and a source of oxidant as further discussedelsewhere herein. Feed gas containing methane (e.g., natural gas) iscontacted with the catalyst material under conditions suitable forinitiation and progression of the reaction within the reactor tocatalyze the conversion of methane to ethylene and other products.

For example, in some embodiments the OCM reactor system comprises one ormore staged reactor vessels operating under isothermal or adiabaticconditions, for carrying out OCM reactions. For adiabatic reactorsystems, the reactor systems may include one, two, three, four, five ormore staged reactor vessels arranged in series, which are fluidlyconnected such that the effluent or “product gas” of one reactor isdirected, at least in part, to the inlet of a subsequent reactor. Suchstaged serial reactors provide higher yield for the overall process, byallowing catalytic conversion of previously unreacted methane. Theseadiabatic reactors are generally characterized by the lack of anintegrated thermal control system used to maintain little or notemperature gradient across the reactor. With no integrated temperaturecontrol system, the exothermic nature of the OCM reaction results in atemperature gradient across the reactor indicative of the progress ofthe reaction, where the inlet temperature can range from about 450° C.to about 600° C., while the outlet temperature ranges from about 700° C.to about 900° C. Typically, such temperature gradients can range fromabout 100° C. to about 450° C. By staging adiabatic reactors, withinterstage cooling systems, one can step through a more completecatalytic reaction without generating extreme temperatures, e.g., inexcess of 900° C.

In operation of certain embodiments, methane-containing feed gas isintroduced into the inlet side of a reactor vessel, e.g., the firstreactor in a staged reactor system. Within this reactor, the methane isconverted into C2+ hydrocarbons, as well as other products, as discussedabove. At least a portion of the product gas stream is then cooled to anappropriate temperature and introduced into a subsequent reactor stagefor continuation of the catalytic reaction. In particular, the effluentfrom a preceding reactor, which in some cases may include unreactedmethane, can provide at least a portion of the methane source for asubsequent reactor. An oxidant source and a methane source, separatefrom the unreacted methane from the first reactor stage, are alsotypically coupled to the inlet of each subsequent reactor.

In alternative aspects, the reactor systems include one or more‘isothermal’ reactors, that maintain a relatively low temperaturegradient across the overall reactor bed, e.g., between the inlet gas andoutlet or product gas, through the inclusion of integrated temperaturecontrol elements, such as coolant systems that contact heat exchangesurfaces on the reactor to remove excess heat, and maintain a flat orinsignificant temperature gradient between the inlet and outlet of thereactor. Typically, such reactors utilize molten salt or other coolantsystems that operate at temperatures below 593° C. As with adiabaticsystems, isothermal reactor systems may include one, two, three or morereactors that may be configured in serial or parallel orientation.Reactor systems for carrying out these catalytic reactions are alsodescribed in U.S. patent application Ser. No. 13/900,898, the fulldisclosure of which is incorporated herein by reference in its entiretyfor all purposes.

The OCM reactor systems used in certain embodiments of the presentinvention also typically include thermal control systems that areconfigured to maintain a desired thermal or temperature profile acrossthe overall reactor system, or individual reactor vessels. In thecontext of adiabatic reactor systems, it will be appreciated that thethermal control systems include, for example, heat exchangers disposedupstream, downstream or between serial reactors within the overallsystem in order to maintain the desired temperature profile across theone or more reactors. In the context of reactors carrying out exothermicreactions, like OCM, such thermal control systems also optionallyinclude control systems for modulating flow of reactants, e.g., methanecontaining feed gases and oxidant, into the reactor vessels in responseto temperature information feedback, in order to modulate the reactionsto achieve the thermal profiles of the reactors within the desiredtemperature ranges. These systems are also described in co-pending U.S.patent application Ser. No. 13/900,898, previously incorporated hereinby reference.

For isothermal reactors, such thermal control systems include theforegoing, as well as integrated heat exchange components, such asintegrated heat exchangers built into the reactors, such as tube/shellreactor/heat exchangers, where a void space is provided surrounding areactor vessel or through which one or more reactor vessels or tubespass. A heat exchange medium is then passed through the void to removeheat from the individual reactor tubes. The heat exchange medium is thenrouted to an external heat exchanger to cool the medium prior torecirculation into the reactor.

Following the OCM process, ethylene optionally may be recovered from theOCM product gas using an ethylene recovery process that separatesethylene present in the product gas from other components, such asresidual, i.e., unreacted methane, ethane, and higher hydrocarbons, suchas propanes, butanes, pentanes and the like. Alternatively, the OCMproduct gas is used in subsequent reactions, as described below, withoutfurther purification or separation of the ethylene. In various otherembodiments, the OCM product gas is enriched for ethylene before beingused in subsequent reactions. In this respect, “enriched” includes, butis not limited to, operations which increases the overall mol % ofethylene in the product gas.

In accordance with the present invention, ethylene derived from methane,e.g., using the above-described OCM processes and systems, is furtherprocessed into higher hydrocarbon compositions, and particularly liquidhydrocarbon compositions. For ease of discussion, reference to OCMprocesses and systems, when referring to their inclusion in an overallprocess flow, from methane to higher hydrocarbon compositions, alsooptionally includes intermediate process steps involved in purificationof ethylene from an OCM product gas, e.g., recycling of product gasesthrough the OCM reactor system, separations of methane and higherhydrocarbons, e.g., NGLs and other C2+ compounds, from the OCM productgas, and the like. Examples of such intermediate processes include, forexample, cryogenic or lean oil separation systems, temperature swingadsorption (TSA), pressure swing adsorption (PSA), and membraneseparations, for separation of different hydrocarbon and othercomponents from ethylene, e.g., CO, CO₂, water, nitrogen, residualmethane, ethane, propane, and other higher hydrocarbon compounds,potentially present in the OCM product gas. Examples of such systems aredescribed in, e.g., U.S. patent application Ser. Nos. 13/739,954,61/773,669 and 61/669,523, the full disclosures of which areincorporated herein by reference in their entirety for all purposes.

FIG. 2 schematically illustrates an exemplary OCM system with integratedseparations system component or components. In particular, shown in FIG.2 is an exemplary process flow diagram depicting a process 200 formethane based C2 production, in a product gas from an OCM reactor orreactors 202, and separation process 204, that includes a firstseparator 206 providing the C2-rich effluent 252 and amethane/nitrogen-rich effluent 274. In the embodiment illustrated inFIG. 2, the OCM product gas from the OCM reactor(s) 202 is compressedthrough compressor 226. The temperature of the compressed OCM productgas 250 is reduced using one or more heat exchangers 210. Thetemperature of the compressed OCM product gas 250 may be reduced throughthe use of an external provided cooling media, introduction of orthermal exchange with a cool process stream, or combinations of these.Reducing the temperature of the OCM product gas 250 will typicallycondense at least a portion of the higher boiling point components inthe compressed OCM product gas 250, including at least a portion of theC2 and heavier hydrocarbon components present in the compressed OCMproduct gas 250.

At least a portion of the condensed high boiling point components can beseparated from the compressed OCM product gas 250 using one or moreliquid gas separators, such as knockout drums 212 to provide an OCMproduct gas condensate 254 and a compressed OCM product gas 256. The OCMproduct gas condensate 254 is introduced to the first separator 206 andat least a portion 258 of the compressed OCM product gas 256 can beintroduced to one or more turboexpanders 214. The isentropic expansionof the compressed OCM product gas 258 within the turboexpanders 214 canproduce shaft work useful for driving one or more compressors or otherdevices in the separation unit 204. The isentropic expansion of thecompressed OCM product gas 258 with the turboexpanders reduces thetemperature of the compressed OCM product gas 260 that exits from theone or more turboexpanders. The compressed OCM product gas 260 from theone or more turboexpanders 214 is introduced to the first separator 206.

The first separator 206 can be any system, device or combination ofsystems and devices suitable for promoting the separation of C2 andheavier hydrocarbons from a gas stream that includes methane andnitrogen. For example, cryogenic distillation at a relatively hightemperature may be used to promote separation of the C2 and heavierhydrocarbons from the methane and nitrogen components in the gas stream.The C2-rich effluent 252 is withdrawn from the first separator 206 and amixed nitrogen and methane containing gas mixture 274 is also withdrawnfrom the first separator 254. The nitrogen content of thenitrogen/methane containing gas mixture 274 withdrawn from the firstseparator 206 can be about 95 mol % or less; about 85 mol % or less;about 75 mol % or less; about 55 mol % or less; about 30 mol % or less.The balance of the nitrogen/methane gas mixture 254 comprisesprincipally methane with small quantities of hydrogen, carbon monoxide,and inert gases such as argon. The nitrogen/methane rich gas 274 is thenfurther cooled using heat exchanger(s) 222, and the coolednitrogen/methane containing gas 276 is then introduced into secondseparator 208, described in more detail, below.

In at least some embodiments, the first separator functions as a“demethanizer” based upon its ability to separate methane from the C2and heavier hydrocarbon components. An exemplary first separator 206includes a vertical distillation column operating at below ambienttemperature and above ambient pressure. In particular, the operatingtemperature and pressure within the first separator 206 can beestablished to improve the recovery of the desired C2 hydrocarbons inthe C2-rich effluent 252. In exemplary embodiments, the first separator206 can have an overhead operating temperature of from about −260° F.(−162° C.) to about −180° F. (−118° C.); about −250° F. (−157° C.) toabout −190° F. (−123° C.); about −240° F. (−151° C.) to about −200° F.(−129° C.; or even from about −235° F. (−148° C.) to about −210° F.(−134° C.) and a bottom operating temperature of from about −150° F.(−101° C.) to about −50° F. (−46° C.); about −135° F. (−93° C.) to about−60° F. (−51° C.); from about −115° F. (−82° C.) to about −70° F. (−57°C.); or about −100° F. (−73° C.) to about −80° F. (−62° C.). In anexemplary aspect, the first separator 206 may operate at pressures offrom about 30 psig (205 kPa) to about 130 psig (900 kPa); about 40 psig(275 kPa) to about 115 psig (790 kPa); about 50 psig (345 kPa) to about95 psig (655 kPa); or about 60 psig (415 kPa) to about 80 psig (550kPa).

The temperature of at least a portion of the C2-rich effluent 252 fromthe first separator 206 can be increased in one or more heat exchangers216, again using an externally supplied heat transfer medium,introduction of, or thermal contact, with a warmer process flow stream,or a combination of these, or other heating systems. The one or moreheat exchanger devices 216 may include any type of heat exchange deviceor system, including but not limited to one or more plate and frame,shell and tube or similar heat exchanger system. After exiting the oneor more heat exchangers 216, the heated C2-rich effluent 252 may be attemperatures of 50° F. (10° C.) or less; 25° F. (−4° C.) or less; about0° F. (−18° C.) or less; about −25° F. (−32° C.) or less; or about −50°F. (−46° C.) or less. Furthermore, the pressure may be about 130 psig(900 kPa) or less; about 115 psig (790 kPa or less; about 100 psig (690kPa) or less; or about 80 psig (550 kPa) or less.

In some embodiments, a portion 262 of the OCM product gas 256 removedfrom the knockout drum 212 and not introduced into the one or moreturboexpanders 214 can be cooled using one or more heat exchangers 218.As noted previously, the heat exchangers may include any type of heatexchanger suitable for the operation. The temperature of the portion 262of the OCM product gas 256 can be decreased using one or morerefrigerants, one or more relatively cool process flows, or combinationsof these. The cooled portion 264 of the OCM product gas 256 containing amixture of nitrogen and methane is introduced into the second separator208.

The second separator 208 may include any system, device or combinationof systems and devices suitable for separating methane from nitrogen.For example, cryogenic distillation at a relatively low temperature canbe used to promote the separation of liquid methane from gaseousnitrogen within the second separator 208. An exemplary second separator208 may include another vertical distillation column operatingsignificantly below ambient temperature and above ambient pressure, andalso generally below the temperature of a cryogenic distillation columnoperating as the first separator, e.g., as described above. For example,the second separator 208 may have an overhead operating temperature offrom about −340° F. (−210° C.) to about −240° F. (−151° C.); from about−330° F. (−201° C.) to about −250° F. (−157° C.); about −320° F. (−196°C.) to about −260° F. (−162° C.); about −310° F. (−190° C.) to about−270° F. (−168° C.); or about 300° F. (−184° C.) to about −280° F.(−173° C.); and a bottom operating temperature of from about −280° F.(−173° C.) to about −170° F. (112° C.); about −270° F. (−168° C.) toabout −180° F. (−118° C.); about −260° F. (−162° C.) to about −190° F.(−123° C.); about −250° F. (−159° C.) to about −200° F. (−129° C.); orabout −240° F. (−151° C. to about −210° F. (−134° C.). In exemplaryembodiments, the second separator 208 will typically operate atpressures of from about 85 psig (585 kPa) or less; about 70 psig (480kPa) or less; about 55 psig (380 kPa) or less; or about 40 psig (275kPa) or less.

The temperature of at least a portion of the methane-rich effluent 266from the second separator 208 can be increased using one or more heatexchangers 220, as described above. After exiting the one or more heatexchangers 220, in exemplary embodiments the temperature of themethane-rich effluent 266 may be about 125° F. (52° C.) or less; about100° F. (38° C.) or less; or about 90° F. (32° C.) or less, while thepressure of the effluent 266 may be about 150 psig (1035 kPa) or less;about 100 psig (690 kPa) or less, or about 50 psig (345 kPa) or less. Inan embodiment, e.g., schematically illustrated in FIG. 2, at least aportion of the methane-rich effluent 266 may be recycled back into thefeedstock gas 268 for the OCM reactor(s) 202, the feedstock gas/oxygenmixture 270 the compressed oxygen containing gas 272 (from compressor228) or directly to the one or more OCM reactors 202.

The temperature of at least a portion of the nitrogen-rich effluent 268from second separator 208 can be increased using one or more heatexchangers 224 like those described above, such that the temperature maybe raised to about 125° F. (52° C.) or less; 100° F. (38° C.) or less;or about 90° F. (32° C.) or less, with a pressure of about 150 psig(1035 kPa) or less; about 100 psig (690 kPa) or less; or about 50 psig(345 kPa) or less.

As will be appreciated, in integrating overall systems, while the one ormore heat exchangers 210, 216, 218, 220, 222 and 224 are illustrated asseparate heat exchange devices, such heat exchangers may be integratedinto one or more integrated systems, where the different temperatureprocess flows may be provided in thermal contact, e.g., as heat exchangemedia for each other, with in the heat exchange device or system. Inparticular, a cooled process flow that is desired to be heated may bepassed through an opposing portion of a heat exchanger from a heatedprocess flow that is desired to be cooled, such that the heat from theheated flow heats the cooler flow, and is, as a result, itself cooled.

Ethylene products of these processes, e.g., in C2-rich effluent 252, arethen subjected to additional processing to yield the desired higherhydrocarbon compositions. For ease of discussion, the processes andsystems for converting ethylene into higher hydrocarbons are referred togenerally as ethylene conversion processes and systems. A number ofexemplary processes for ethylene conversion are described in greaterdetail below.

III. Integrated and Selectable Ethylene Conversion

As noted previously, in the context of certain aspects of the invention,the conversion of methane to ethylene, as well as the conversion ofethylene to higher hydrocarbon compositions, is carried out inintegrated processes. As used herein, integrated processes refer to twoor more processes or systems that are fluidly integrated or coupledtogether. Thus, within this aspect of the invention, the process forconversion of methane to ethylene is fluidly connected to one or moreprocesses for ethylene conversion to one or more higher hydrocarboncompounds. Fluid integration or fluid coupling generally refers to apersistent fluid connection or fluid coupling between two systems withinan overall system or facility. Such persistent fluid communicationtypically refers to an interconnected pipeline network coupling onesystem to another. Such interconnected pipelines may also includeadditional elements between two systems, such as control elements, e.g.,heat exchangers, pumps, valves, compressors, turbo-expanders, sensors,as well as other fluid or gas transport and/or storage systems, e.g.,piping, manifolds, storage vessels, and the like, but are generallyentirely closed systems, as distinguished from two systems wherematerials are conveyed from one to another through any non-integratedcomponent, e.g., railcar or truck transport, or systems that are notco-located in the same facility or immediately adjacent facilities. Asused herein, fluid connection and/or fluid coupling includes completefluid coupling, e.g., where all effluent from a given point such as anoutlet of a reactor, is directed to the inlet of another unit with whichthe reactor is fluidly connected. Also included within such fluidconnections or couplings are partial connections, e.g., where only aportion of the effluent from a given first unit is routed to a fluidlyconnected second unit. Further, although stated in terms of fluidconnections, it will be appreciated that such connections includeconnections for conveying either or both of liquids and/or gas.

In accordance with certain aspects of the invention, a methane toethylene conversion process is not just integrated with a singleethylene conversion process, but instead, is integrated with multiple(i.e., two or more) different ethylene conversion processes or systems.In particular, ethylene produced from a single methane feed stream maybe converted to multiple different products using multiple differentethylene conversion processes. For example, in some embodiments a singleOCM reactor system is fluidly connected to one, two, three, four, fiveor more different catalytic or other reactor systems for furtherconversion of the ethylene containing product of the OCM reactor system(also referred to herein as the “ethylene product”) to multipledifferent higher hydrocarbon compositions.

In certain aspects, the ethylene product is selectively directed inwhole or in part to any one or more of the various ethylene conversionprocesses or systems integrated with the OCM reactor system. Forexample, at any given time all of the ethylene product produced throughan OCM reactor system may be routed through a single process.Alternatively, a portion of the ethylene product may be routed through afirst ethylene conversion process or system, while some or all of theremaining ethylene product is routed through one, two, three, four ormore different ethylene conversion systems.

Although described in terms of directing ethylene streams to a single ormultiple different ethylene conversion processes, in certain preferredaspects, those ethylene streams may be relatively dilute ethylenestreams, e.g., that contain other components in addition to ethylene,such as other products of the OCM reaction, unreacted feed gases, orother by products. Typically, such other components may includeadditional reaction products, unreacted feedgases, or other reactoreffluents from an ethylene production process, e.g., OCM, such asmethane, ethane, propane, propylene, CO, CO₂, O₂, N₂, H₂, and/or water.The use of dilute ethylene streams, and particularly those containingother hydrocarbon components is particularly advantageous in theethylene conversion processes used in conjunction with the invention. Inparticular, because these ethylene conversion processes utilize moredilute and less pure streams, the incoming ethylene streams are notrequired to go through as stringent a separations process or processesas would typically be required for other processes intended to producehigher purity ethylene, e.g., cryogenic separations systems, lean oilseparators, TSA and PSA based separations processes. These separationsprocesses typically have relatively high capital costs that scale, atleast in part, based upon the volume of incoming gases. As such,separation processes for highly dilute ethylene streams can havesubstantially high capital and operating costs associated with them. Byproviding less stringent separations requirements on these ethylenestreams, one can substantially reduce the capital costs. Further,because the ethylene conversion processes used in conjunction with theinvention typically result in the production of desired liquidhydrocarbons, subsequent separation of gas co-products, or unreactedfeed gases is made much simpler.

In addition to reducing capital and operating costs, the use of ethylenestreams that comprise additional hydrocarbon components can enhance theproduct slate emanating from the ethylene conversion processes throughwhich those ethylene streams are routed. In particular, the presence ofhigher order hydrocarbons, C3, C4, C5, etc. in the ethylene streamsentering into the ethylene conversion processes can improve the overallefficiency of those processes, by providing enriched starting materials,and also affects the overall carbon efficiency of the OCM and ethyleneconversion processes, by ensuring that a greater fraction of the carboninput is converted to higher hydrocarbon products.

While ethylene streams being routed to the ethylene conversion processesof the invention may range anywhere from trace concentrations ofethylene to pure or substantially pure ethylene, e.g., approaching 100%ethylene, the dilute ethylene streams described herein may generally becharacterized as having anywhere from about 1% to about 50% ethylene,preferably, between about 5% and about 25% ethylene, and in furtherpreferred aspects, between about 10% and about 25% ethylene, in additionto other components. In other embodiments, the ethylene feed gascomprises less than about 5% ethylene, for example less than about 4%,less than about 3%, less than about 2% or even less than about 1%ethylene. In some embodiments, the dilute ethylene product gasesemployed in the ethylene conversion processes further comprise one ormore gases which are either produced during the OCM reaction or areunreacted during the OCM process. For example, in some embodiments theproduct gas comprises ethylene at any of the foregoing concentrationsand one or more gas selected from CO₂, CO, H₂, H₂O, C₂H₆, CH₄ and C3+hydrocarbons. In certain embodiments, such dilute ethylene feed gasses,which optionally include one or more of the foregoing gases areadvantageous for use in reactions comprising conversion of ethylene tohigher olefins and/or saturated hydrocarbons, for example conversion ofethylene to liquid fuels such as gasoline diesel or jet fuel at higherefficiencies (e.g., from methane) than previously attainable.

By utilizing dilute ethylene streams to feed into one or more ethyleneconversion processes, one eliminates the need to separate or purify theethylene coming into the process, e.g., as a product of an OCM reactionprocess. The elimination of additional costly process steps isparticularly useful where the ethylene conversion processes are used toproduce lower margin products, such as gasoline, diesel or jet fuel orblendstocks for these fuels. In particular, where the desired product isa lower value product, one may pass the OCM feed gases directly into oneor more ethylene conversion processes that produce hydrocarbon mixturesthat can be used as gasoline, diesel fuel or jet fuel or theirblendstocks. Such direct passage may be in the absence of anyintermediate purification steps, such as any processes used for theremoval of the above described impurities. Alternatively, it may includecertain purification steps to separate out some or all of thenon-hydrocarbon impurities, e.g., N₂, CO₂, CO, H₂, etc. The directpassage may avoid any hydrocarbon fractionation, including removal ofany of C1, C2, C3, C4 compounds, etc., or it may include somefractionation, e.g., to enhance carbon efficiency. For example, suchincluded fractionation may include separation of methane and or ethanefrom the OCM effluent gas to recycle back to the OCM process. Inaddition to the foregoing, the presence of additional components such asCO₂, H₂O and H₂ in the feed streams would also be expected to improvecatalyst lifetime in the ethylene conversion processes by reducingdeactivation, thereby requiring fewer catalyst regeneration cycles.

In contrast, where one desires to produce more selectively purecompounds, e.g., aromatic compounds, one will often need to pretreat thefeed gases to remove many of the non-ethylene impurities.

Other components of these dilute ethylene streams may includeco-products of the ethylene production processes, e.g., OCM reactions,such as other C2+ hydrocarbons, like ethane, propane, propylene, butane,pentane, and larger hydrocarbons, as well as other products such as CO,CO₂, H₂, H₂O, N₂, and the like.

A variety of different ethylene conversion processes may be employed inthe various aspects of the present invention to produce higherhydrocarbon materials for use in, e.g., chemical manufacturing, polymerproduction, fuel production, as well as a variety of other products. Inparticular, the ethylene produced using the OCM processes may beoligomerized and/or reacted by a variety of different processes andreactor systems for producing linear alpha-olefins (LAOs), olefiniclinear and/or olefinic branched hydrocarbons, saturated linear and/orbranched hydrocarbons, saturated and/or olefinic cyclic hydrocarbons,aromatic hydrocarbons, oxygenated hydrocarbons, halogenatedhydrocarbons, alkylated aromatics, and/or hydrocarbon polymers.

A. Olefinic Products and Processes

As noted above, the ethylene conversion processes employed in theintegrated processes and systems of the invention may produce olefinicproducts for use in a variety of different end products or applications.For example, a portion or all of the ethylene produced by the OCMprocess may be routed through one or more catalytic processes or systemsto oligomerize ethylene into LAOs of ranging carbon numbers. Thesecompounds are particularly useful in chemical manufacturing, e.g., inthe production of amines, amine oxides, oxo-alcohols, alkylatedaromatics epoxides, tanning oils, synthetic lubricants, lubricantadditives, alpha olefin sulfonates, mercaptans, organic alkyl aluminum,hydrogenated oligomers, and synthetic fatty acids. Alternatively oradditionally, the ethylene may be oligomerized through LAO processes toproduce C4-C20 LAOs for use as liquid blend stocks for gasoline, dieselor jet fuels. These LAOs can also be hydrogenated to linear alkanes forfuel blend stocks for gasoline, jet, and diesel fuel.

Processes used for the production of product ranges, e.g., C4-C30 LAOS,are generally referred to herein as “full range processes” or “narrowrange processes”, as they produce a range of chemical species, e.g.,LAOs of varying chain length such as 1-butene, 1-hexene, 1-octene,1-decene, etc., in a single process. Products from full range or narrowrange processes may be distilled or fractionated into, e.g., C4-C10 LAOsfor use as chemical process feedstocks, C10-C20 LAOs for use as a jetfuel blendstock, diesel fuel blendstock, and chemical feedstock. Bycontrast, processes that produce a single product species in high yield,e.g., LAO of a single chain length such as 1-butene, 1-hexene, 1-octene,1-decene or the like, are referred to generally as selective processes.

Full and narrow ranges of products may be prepared from ethylene using avariety of LAO processes, such as, for example, the α-Sablin® process(See, e.g., Published International Patent Application No. WO2009/074203, European Patent No. EP 1749806B1, and U.S. Pat. No.8,269,055, the full disclosures of which are incorporated herein byreference in their entirety for all purposes), the Shell higher olefinprocess (SHOP), the Alphabutol process, the Alphahexyl process, theAlphaSelect process, the Alpha-Octol process, Linear-1 process, theLinealene process, the Ethyl Process, the Gulftene process, and thePhillips 1-hexene process.

Briefly, the α-Sablin process employs a two-component catalyst system ofa zirconium salt and an aluminum alkyl co-catalyst, for homogenous,liquid phase oligomerization of ethylene to a narrow range of LAOS. Thecatalytic cycle comprises a chain growth step by an ethylene insertionreaction at the co-ordination site and displacement of the co-ordinatedhydrocarbon from the organometallic complex. The ratio of zirconium toaluminum can be used to adjust between chain growth and displacement,thereby adjusting the product spectrum more toward lighter or heavierLAOS. For example, with a high Zr:Al ratio, the product spectrum can beshifted to upwards of 80% C4-C8 LAOS, while lower Zr:Al ratios willshift the product spectrum towards heavier LAOS. The reaction isgenerally carried out in a bubble column reactor with a solvent, such astoluene, and catalyst being fed into the liquid phase at temperatures ofbetween about 60° C. and 100° C. and pressures of between about 20 barand 30 bar. The liquid LAOs are then sent to a separation train todeactivate the catalyst, separate the solvent and optionally perform anyadditional product separations that are desired.

Additionally, as noted above, all or a portion of these olefinicproducts may be hydrogenated prior to distillation to convert theolefins into the corresponding alkanes for use as alkane blendstocks forfuel products, and then again, subjected to a distillation or otherseparation process to produce the desired products.

In various other embodiments, a wide range of other ethylene conversionprocesses may likewise be integrated at the back end of the OCMprocesses described above, depending upon the desired product orproducts for the overall process and system. For example, as notedabove, in alternative or additional aspects, an integrated ethyleneconversion process for production of LAOs may include the SHOP system, afull range ethylene conversion process which may be used to produce LAOsin the C6-C16 range. Briefly, the SHOP system employs a nickel-phosphinecomplex catalyst to oligomerize ethylene at temperatures of from about80° C. to about 120° C., and pressures of from about 70 bar to about 140bar.

A variety of other full-range ethylene conversion processes may beemployed in the context of the invention, including without limitation,the AlphaSelect process, the Alpha-Octol process, Linear-1 process, theLinealene process, the Synthol process, the Ethyl Process, the Gulfteneprocess, the Phillips 1-hexene process, and others. These processes arewell characterized in the literature, and reported, for example at theNexant/Chemsystems PERP report, Alpha Olefins, January 2004, the fulldisclosure of which are incorporated herein by reference in theirentirety for all purposes.

As an alternative or in addition to full and/or narrow range ethyleneconversion processes, ethylene conversion processes that may beintegrated into the overall systems of the invention include processesfor the selective production of high purity single compound LAOcompositions. As used herein, processes that are highly selective forthe production of a single chemical species are generally referred to asselective or “on purpose” processes, as they are directed at productionof a single chemical species in high selectivity. In the context of LAOproduction, such on purpose processes will typically produce a singleLAO species, e.g., 1-butene, 1-hexene, 1-octene, etc., at selectivitiesof greater than 50%, in some cases greater than 60%, greater than 75%,and even greater than 90% selectivity for the single LAO species.

Examples of such on purpose processes for ethylene conversion to LAOsinclude, for example, the Alphahexyl process from IFP, the Alphabutolprocess, or the Phillips 1-hexene process for the oligomerization ofethylene to high purity 1-hexene, as well as a wide range of other knownprocesses that may be integrated with the overall OCM reactor system.

The Alphahexyl process, for example, is carried out using phenoxideligand processes. In particular, ethylene trimerization may be carriedout using a catalytic system that involves a chromium precursor, aphenoxyaluminum compound or alkaline earth phenoxide and atrialkylaluminum activator at 120° C. and 50 bar ethylene pressure (See,e.g., U.S. Pat. No. 6,031,145, and European Patent No. EP1110930, thefull disclosures of which are incorporated herein by reference in theirentirety for all purposes). Likewise, the Phillips 1-hexene processemploys a chromium(III) alkanoate, such as chromiumtris(2-ethylhexanoate, pyrrole, such as 2,5-dimethylpyrrole, and Et₃Alto produce 1-hexene at high selectivity, e.g., in excess of 93%. See,e.g., European Patent No. EP0608447 and U.S. Pat. No. 5,856,257, thefull disclosures of which are incorporated herein by reference in theirentirety for all purposes. A variety of other ethylene trimerizationprocesses may be similarly integrated to the back end of the OCM systemsdescribed herein. These include, for example, the British Petroleum PNPtrimerization system (see, e.g., Published International PatentApplication No. WO 2002/04119, and Carter et al., Chem. Commun. 2002,858), and Sasol PNP trimerization system (see, e.g., PublishedInternational Patent Application No. WO2004/056479, discussed in greaterdetail), the full disclosures of which are incorporated herein byreference in their entirety for all purposes.

The Alphabutol process employs a liquid phase proprietary solublecatalyst system of Ti(IV)/AlEt3, in the dimerization of ethylene to1-butene at relatively high purity, and is licensed through Axens(Rueil-Malmaison, France). Ethylene is fed to a continuous liquid phasedimerization reactor. A pump-around system removes the exothermic heatof reaction from the reactor. The reactor operates between 50-60° C. at300-400 psia. The catalyst is removed from the product effluent and isultimately fed to the 1-butene purification column where comonomer-grade1-butene is produced.

Still other selective ethylene conversion processes include thecatalytic tetramerization of ethylene to 1-octene. For example, oneexemplary tetramerization process employs a liquid phase catalyticsystem using a Cr(III) precursor, such as [Cr(acac)3] or [CrCl3(THF)₃]in conjunction with a bis(phosphine)amine ligand and amethylaluminooxane (MAO) activator at temperatures of between about 40°C. and 80° C. and ethylene pressures of from 20 to 100 bar, to produce1-octene with high selectivity. See, e.g., Published InternationalPatent Application No. WO2004/056479 and Bollmann, et al., “EthyleneTetramerization: A New Route to Produce 1-Octene in Exceptionally HighSelectivities” J. Am. Chem. Soc., 2004, 126 (45), pp 14712-14713, thefull disclosures of which are incorporated herein by reference in theirentirety for all purposes.

In addition to the LAO processes described above, ethylene produced fromthe integrated OCM reactor systems can also be used to make olefinicnon-LAO linear hydrocarbons and branched olefinic hydrocarbons throughthe same or different integrated processes and systems. For example, theethylene product from the OCM reactor system may be passed throughintegrated reactor systems configured to carry out the SHOP process, theAlphabutol process, the Alphahexyl process, the AlphaSelect process, theAlpha-Octol process, Linear-1 process, the Linealene process, the EthylProcess, the Gulftene process, and/or the Phillips 1-hexene process, toyield the resultant LAO products. The output of these systems andprocesses may then be subjected to an olefin isomerization step to yieldlinear olefins other than LAOS, branched olefinic hydrocarbons, or thelike. In addition, olefinic non-LAO linear hydrocarbons and branchedolefinic hydrocarbons can be prepared by ethylene oligomerization overheterogeneous catalysts such as zeolites, amorphous silica/alumina,solid phosphoric acid catalysts, as well as doped versions of theforegoing catalysts.

Other oligomerization processes have been described in the art,including the olefin oligomerization processes set forth in PublishedU.S. Patent Application No. 2012/0197053 (incorporated herein byreference in its entirety for all purposes), which describes processesused for production of liquid fuel components from olefinic materials.

Although a number of processes are described with certain specificity,that description is by way of example and not limitation. In particular,it is envisioned that the full range of ethylene oligomerization and/orconversion processes may be readily integrated onto the back end of theOCM reactor systems for conversion of methane to ethylene product, andsubsequently to a wide range of different higher hydrocarbon products.As noted previously, certain embodiments of the ethylene conversionprocesses that are integrated into the overall systems of the inventionare those that yield liquid hydrocarbon products. Other embodiments ofthe ethylene conversion processes that are integrated in the overallsystems include process that are particularly well-suited for use withdilute ethylene feed stocks which optionally comprise additionalcomponents such as higher hydrocarbons, unreacted OCM starting material(methane and/or other natural gas components) and/or side products ofthe OCM reactions. Examples of such other components are provided above.

B. Non-Olefinic Products and Processes

In addition to or as an alternative, the ethylene product produced fromthe OCM reactor system may be routed through one or more catalytic orother systems and processes to make non-olefinic hydrocarbon products.For example, as noted above, saturated linear and branched hydrocarbonproducts may be produced from the ethylene product of the OCM reactorsystem through the hydrogenation of the products of the olefinicprocesses described above, e.g., the SHOP process, the Alphabutolprocess, the Alphahexyl process, the AlphaSelect process, theAlpha-Octol process, Linear-1 process, the Linealene process, the EthylProcess, the Gulftene process, and/or the Phillips 1-hexene process.

Other catalytic ethylene conversions systems that may likewise beemployed include reacting ethylene over heterogeneous catalysts, such aszeolites, amorphous silica/alumina, solid phosphoric acid catalysts,and/or doped forms of these catalysts, to produce mixtures ofhydrocarbons, such as saturated linear and/or branched hydrocarbons,saturated olefinic cyclic hydrocarbons, and/or hydrocarbon aromatics. Byvarying the catalysts and or the process conditions, selectivity of theprocesses for specific components may be enhanced. For example, ethylenepurified from OCM effluent or unpurified OCM effluent containingethylene can be flowed across a zeolite catalyst, such as ZSM-5, oramorphous silica/alumina material with SiO₂/Al₂O₃ ratios of 23-280, atethylene partial pressures between 0.01 bar to 100 bar (undoped, ordoped with Zn and/or Ga in some embodiments or some combination thereof)at temperatures above 350° C. to give high liquid hydrocarbon yield(80+%) and high aromatic selectivity (benzene, toluene, xylene (BTX)selectivity >90% within the liquid hydrocarbon fraction). Ethylenepurified from OCM effluent or unpurified OCM effluent containingethylene can be flowed across a zeolite catalyst, such as ZSM-5, oramorphous silica/alumina material with SiO₂/Al₂O₃ ratios of 23-280, atethylene partial pressures between 0.01 bar to 100 bar (undoped, or withdopants including but not limited to, e.g., Ni, Mg, Mn, Ca, and Co, orsome combination of these) at temperatures above 200° C., to give highliquid hydrocarbon yield (80+%) and high gasoline selectivity (gasolineselectivity >90% within the liquid hydrocarbon fraction). Ethylenepurified from OCM effluent or unpurified OCM effluent containingethylene can be flowed across a zeolite catalyst, such as ZSM-5, oramorphous silica/alumina material with SiO₂/Al₂O₃ ratios of 23-280 or asolid phosphoric acid catalyst, at ethylene partial pressures between0.01 bar to 100 bar at temperatures above 200° C. to give high liquidhydrocarbon yield (80+%) and high distillate selectivity (gasolineselectivity >90% within the liquid hydrocarbon fraction).

In some embodiments, to achieve high jet/diesel fuel yields, a twooligomerization reactor system is used in series. The firstoligomerization reactor takes the ethylene and oligomerizes it to C3-C6olefins over modified ZSM-5 catalysts, e.g., Mg, Ca, or Sr doped ZSM-5catalysts. The C3-C6 olefins can be the end products of the process oralternatively can be placed in a second oligomerization reactor to becoupled into jet/diesel fuel range liquid.

In addition to the foregoing processes and systems, some embodiments ofthe ethylene conversion processes also include processes for productionof oxygenated hydrocarbons, such as alcohols and/or epoxides. Forexample, the ethylene product can be routed through an integrated systemthat includes a heterogeneous catalyst system, such as a solidphosphoric acid catalyst in the presence of water, to convert theethylene to ethanol. This process has been routinely used to produce 200proof ethanol in the process used by LyondellBasell. In otherembodiments, longer chain olefins and/or LAO's, derived from OCMethylene by oligomerization, can be likewise converted to alkyl alcoholsusing this same process. See, e.g., U.S. Pat. Nos. 2,486,980; 3,459,678;4,012,452, the full disclosures of which are incorporated herein byreference in their entirety for all purposes. In alternate embodiments,ethylene undergoes a vapor oxidation reaction to make ethylene oxideover a silver based catalyst at 200-300° C. at 10-30 atmospheres ofpressure with high selectivity (80+%). Ethylene oxide is an importantprecursor for synthesis of ethylene glycol, polyethylene glycol,ethylene carbonate, ethanolamines, and halohydrins. See, e.g.,Chemsystems PERP Report Ethylene Oxide/Ethylene Glycol 2005.

In still other aspects, the ethylene product produced from the OCMreactor system may be routed to a reactor system that reacts theethylene with various halogen sources (acids, gases, and others) to makehalogenated hydrocarbons useful, for example, as monomers in producinghalogenated polymers, such as polyvinyl chloride (PVC). For example, inone ethylene dichloride (EDC) process, available from ThyssenKrupp Uhde,ethylene can be reacted with chlorine gas to make EDC, an importantprecursor to vinyl-chloride monomer (VCM) for polyvinylchloride (PVC)production. This process also can be modified EDC to react ethylene withhydrochloric acid (HCl) to make EDC via oxychlorination.

In still other exemplary ethylene conversion processes, the ethyleneproduct of the OCM reactor system may be converted to alkylated aromatichydrocarbons, which are also useful as chemical and fuel feedstocks. Forexample, in the Lummus CD-Tech EB process and the Badger EB process,benzene can be reacted with OCM ethylene, in the presence of a catalyst,to make ethylbenzene. See, e.g., U.S. Pat. No. 4,107,224, the fulldisclosure of which is incorporated herein by reference in its entiretyfor all purposes. Ethylbenzene can be added to gasoline as a high-octanegasoline blendstock or can be dehydrogenated to make styrene, theprecursor to polystyrene.

In addition to the liquid and other hydrocarbons described above, incertain aspects, one or more of the integrated ethylene conversionprocesses is used to convert ethylene product from the OCM reactorsystem to one or more hydrocarbon polymers or polymer precursors. Forexample, in some embodiments ethylene product from the integrated OCMreactor systems is routed through an integrated Innovene process system,available through Ineos Technologies, Inc., where the ethylene ispolymerized in the presence of a catalyst, in either a slurry or gasphase system, to make long hydrocarbon chains or polyethylene. Byvarying the process conditions and catalyst the process and system canbe used to produce high density polyethylene or branched low densitypolyethylene, etc. The Innovene G and Innovene S processes are describedat, for example, at “Ineostechnologies.com”. See also Nexant/ChemsystemsHDPE Report, PERP 09/10-3, January 2011, the full disclosure of which isincorporated herein by reference in its entirety for all purposes.

Alternatively, ethylene from OCM can be introduced, under high pressure,into an autoclave or tubular reactor in the presence of a free radicalinitiator, such as O₂ or peroxides, to initiate polymerization for thepreparation of low-density polyethylene (LDPE). See e.g., “AdvancedPolyethylene Technologies” Adv Polym Sci (2004) 169:13-27, the fulldisclosure of which is incorporated herein by reference in its entiretyfor all purposes. Alternatively, ethylene from OCM can be introduced,under low pressure in the presence of a chromium oxide based catalyst,Ziegler-Natta catalyst, or a single-site (metallocene or non metallocenebased) catalyst, to prepare HDPE, MDPE, LLDPE, mLLDPE, or bimodalpolyethylene. The reactor configurations for synthesis of HDPE, LLDPE,MDPE, and biomodal PE can be a slurry process, in which ethylene ispolymerized to form solid polymer particles suspended in a hydrocarbondiluent, a solution process in which dissolved ethylene is polymerizedto form a polymer dissolved in solvent, and/or a gas phase process inwhich ethylene is polymerized to form a solid polymer in a fluidized bedof polymer particles. Ethylene from OCM can be co-polymerized withdifferent monomers to prepare random and block co-polymers. Co-monomersfor ethylene copolymerization include but are not limited to: at leastone olefin comonomer having three to fifteen carbons per molecule(examples are propylene and LAO's such as 1-butene, 1-hexene, 1-octene),oxygenated co-monomers such as: carbon oxide; vinyl acetate, methylacrylate; vinyl alcohols; allyl ethers; cyclic monomers such as:norbornene and derivatives thereof; aromatic olefins such as: styreneand derivatives thereof. These ethylene or LAO copolymerizationprocesses, e.g., where ethylene is copolymerized with differentmonomers, are generally referred to herein as copolymerization processesor systems.

More exemplary ethylene conversion processes that may be integrated withthe OCM reactor systems include processes and systems for carrying outolefin metathesis reactions, also known as disproportionation, in theproduction of propylene. Olefin metathesis is a reversible reactionbetween ethylene and butenes in which double bonds are broken and thenreformed to form propylene. “Propylene Production via Metathesis,Technology Economics Program” by Intratec, ISBN 978-0-615-61145-7, Q22012, the full disclosure of which is incorporated herein by referencein its entirety for all purposes. Propylene yields of about 90 wt % areachieved. This option may also be used when there is no butenefeedstock. In this case, part of the ethylene from the OCM reactionfeeds into an ethylene-dimerization unit that converts ethylene intobutene.

As noted previously, one, two, three, four or more different ethyleneconversion processes are provided integrated into the overall systems ofthe invention, e.g., as shown in FIG. 1. As will be appreciated, theseethylene conversion systems will include fluid communications with theOCM systems described above, and may be within the same facility orwithin an adjacent facility. Further, these fluid communications may beselective. In particular, in certain embodiments the interconnectbetween the OCM system component and the ethylene conversion systemcomponent(s) is able to selectively direct all of an ethylene productfrom the OCM system to any one ethylene conversion system at a giventime, and then direct all of the ethylene product to a second differentethylene conversion system component at a different time. Alternatively,such selective fluid communications may also simultaneously directportions of the ethylene product to two or more different ethyleneconversion systems to which the OCM system is fluidly connected.

These fluid communications will typically comprise interconnected pipingand manifolds with associated valving, pumps, thermal controls and thelike, for the selective direction of the ethylene product of the OCMsystem to the appropriate ethylene conversion system component orcomponents.

C. Catalysts

In certain aspects, the present invention also provides novel catalystsand catalyst compositions for ethylene conversion processes, inaccordance with the above-described processes or modifications thereof.In particular, the invention provides modified zeolite catalysts andcatalyst compositions for carrying out a number of desired ethyleneconversion reaction processes. In particular, provided are impregnatedor ion exchanged zeolite catalysts useful in conversion of ethylene tohigher hydrocarbons, such as gasoline or gasoline blendstocks, dieseland/or jet fuels, as well as a variety of different aromatic compounds.For example, where one is using ethylene conversion processes to convertOCM product gases to gasoline or gasoline feedstock products or aromaticmixtures, one may employ modified ZSM catalysts, such as ZSM-5 catalystsmodified with Ga, Zn, Al, or mixtures thereof. In particularly preferredaspects, Ga, Zn and/or Al modified ZSM-5 catalysts are preferred for usein converting ethylene to gasoline or gasoline feedstocks. Modifiedcatalyst base materials other than ZSM-5 may also be employed inconjunction with the invention, including, e.g., Y, ferrierite,mordenite, and additional catalyst base materials described below.

In other aspects, ZSM catalysts, such as ZSM-5 are modified with Co, Fe,Ce or mixtures of these and are used in ethylene conversion processesusing dilute ethylene streams that include both carbon monoxide andhydrogen components (See, e.g., Choudhary, et al., Microporous andMesoporous Materials 2001, 253-267). In particular, these catalysts arecapable of co-oligomerizing the ethylene and syngas components intohigher hydrocarbons, and particularly mixtures useful as gasoline,diesel or jet fuel or blendstocks of these. In such embodiments, a mixedstream that includes dilute or non-dilute ethylene concentrations alongwith CO/H₂ gases is passed over the catalyst under conditions that causethe co-oligomerization of both sets of feed components. Use of ZSMcatalysts for conversion of syngas to higher hydrocarbons is describedin, for example, Li, et al., Energy and Fuels 2008, 22:1897-1901.

D. Reactor Systems

Reactor systems for carrying out ethylene conversion processes inaccordance with the invention are also provided. A number of ethyleneconversion processes employed in conjunction with the invention involveexothermic catalytic reactions where substantial heat is generated bythe process. Likewise, for a number of these catalytic systems, theregeneration processes for the catalyst materials likewise involveexothermic reactions. As such, reactor systems for use in theseprocesses will generally be configured to effectively manage excessthermal energy produced by the reactions, in order to control thereactor bed temperatures to most efficiently control the reaction,prevent deleterious reactions, and prevent catalyst or reactor damage ordestruction.

As a general matter, tubular reactor configurations that present highwall surface area per unit volume of catalyst bed may generally be usedfor reactions where thermal control is desirable, as they permit greaterthermal transfer out of the reactor. In accordance with the invention,reactor systems that include multiple parallel tubular reactors may beused in carrying out the ethylene conversion processes described herein.In particular, arrays of parallel tubular reactors each containing theappropriate catalyst for one or more ethylene conversion reactionprocesses may be arrayed with space between them to allow for thepresence of a cooling medium between them. Such cooling medium mayinclude any cooling medium appropriate for the given process. Forexample, the cooling medium may be air, water or other aqueous coolantformulations, steam, oil, or for very high temperature reactor systems,molten salt coolants. Heat exchange may additionally, or alternativelybe provided to the feed gases, effluent gases, or all of them.

In one aspect, reactor systems are provided that include multipletubular reactors segmented into one, two, three, four or more differentdiscrete cooling zones, where each zone is segregated to contain itsown, separately controlled cooling medium. The temperature of eachdifferent cooling zone may be independently regulated through itsrespective cooling medium and an associated temperature control system,e.g., thermally connected heat exchangers, etc. Such differentialcontrol of temperature in different reactors can be used todifferentially control different catalytic reactions, or reactions thathave catalysts of different age. Likewise, it allows for the real timecontrol of reaction progress in each reactor, in order to maintain amore uniform temperature profile across all reactors, and thereforesynchronize catalyst lifetimes, regeneration cycles and replacementcycles.

Differentially cooled tubular reactor systems are schematicallyillustrated in FIG. 4. As shown, an overall reactor system 400, includesmultiple discrete tubular reactors 402, 404, 406, 408 contained within alarger reactor housing 410. Within each tubular reactor is disposed acatalyst bed for carrying out a desired catalytic reaction. The catalystbed in each tubular reactor may include the same catalyst composition orit may be different from the catalyst in the other tubular reactors,e.g., optimized for catalyzing a different reaction, or for catalyzingthe same reaction under different conditions. For example, in thecontext of the present invention, each different reactor tube mayoptionally include a catalyst or catalytic system for carrying out adifferent ethylene conversion process as described elsewhere herein.

As shown, the multiple tubular reactors 402, 404, 406, 408 share acommon manifold 412 for the delivery of reactants to the reactors.However, each individual tubular reactor or subset of the tubularreactors may alternatively include a single reactant delivery conduit ormanifold for delivering reactants to that tubular reactor or subset ofreactors, while a separate delivery conduit or manifold is provided fordelivery of the same or different reactants to the other tubularreactors or subsets of tubular reactors. Each of the different tubularreactors is separately temperature controlled, e.g., by its inclusionwithin a different temperature control zone which surround the reactors,e.g., zones 414, 416, 418, 420. Such control may be passive, e.g., bysuch zones proximity to other zones, or they may be actively controlledby being coupled to an appropriate temperature control system, e.g.,such as heat exchanger 422 shown for temperature control zone 420, whichmay provide appropriately controlled cooling media, e.g., air, steam,molten salt, etc.

In an additional or alternative aspect, the reactor systems used inconjunction with the ethylene conversion processes described hereinprovide for variability in residence time for reactants within thecatalytic portion of the reactor. In general, one can vary residencetime within a reactor through the variation of any of a number ofdifferent applied parameters, e.g., increasing or decreasing flow rates,pressures, reactor catalyst bed lengths, etc. In accordance with certainaspects of the invention, however, a single reactor system may beprovided with variable residence times, despite sharing a single reactorinlet, by varying the volume of different reactor tubes/catalyst beds orreactor tube portions within a single reactor unit. As a result ofvaried volumes among reactor tubes or reactor tube portions into whichreactants are being introduced at a given flow rate, residence times forthose reactants within those varied volume reactor tubes or reactor tubeportions, will be consequently varied.

Variation of reactor volumes may be accomplished through a number ofapproaches. By way of example, varied volume may be provided byincluding two or more different reactor tubes into which reactants areintroduced at a given flow rate, where the two or more reactor tubeseach have different volumes, e.g., by providing varied diameters. Aswill be appreciated, the residence time of gases being introduced at thesame flow rate into two or more different reactors having differentvolumes will be different. In particular, the residence time will begreater in the higher volume reactors and shorter in the smaller volumereactors. The higher volume within two different reactors may beprovided by providing each reactor with different diameters. Likewise,in different embodiments y the length of the reactors catalyst bed isvaried, in order to vary the volume of the catalytic portion.

Alternatively, or additionally, one can vary the volume of an individualreactor tube by varying the diameter of the reactor along its length,effectively altering the volume of different segments of the reactor.Again, in the wider reactor segments, the residence time of gas beingintroduced into the reactor tube will be longer in the wider reactorsegments than in the narrower reactor segments.

In a related aspect, varied volumes can also be provided by routingdifferent inlet reactant streams to different numbers of similarly sizedreactor conduits or tubes. In particular, reactants, e.g., gases, may beintroduced into a single reactor tube at a given flow rate to yield aparticular residence time within the reactor. In contrast, reactantsintroduced at the same flow rate into two or more parallel reactor tubeswill have a much longer residence time within those reactors.

The above-described approaches to varying residence time within reactorcatalyst beds are illustrated with reference to FIGS. 5 and 6.

FIG. 5 schematically illustrates a reactor system 500 in which two ormore tubular reactors 502 and 504 are disposed, each having its owncatalyst bed, 506 and 508, respectively, disposed therein. The tworeactors are connected to the same inlet manifold such that the flowrate of reactants being introduced into each of reactors 502 and 504 arethe same. Because reactor 504 has a larger volume (shown as a widerdiameter), the reactants will be retained within catalyst bed 508 for alonger period. In particular, as shown, reactor 504 has a largerdiameter, resulting in a slower linear velocity of reactants through thecatalyst bed 508, than the reactants passing through catalyst bed 506.As noted above, one could similarly increase residence time within thecatalyst bed of reactor 504 by providing a longer reactor catalyst bed.However, such longer reactor bed would be required to have similar backpressure as a shorter reactor to ensure reactants are introduced at thesame flow rate as the shorter reactor.

In FIG. 6 is schematically illustrated an alternative approach tovarying reactor volumes in order to vary residence time of reactants inthe catalyst bed. As shown, an individual reactor unit, e.g., reactortube 602, is configured to provide for differing residence times withindifferent portions of the reactor tube by varying the diameter of thereactor between reactor segment 604, 606 and 608. In particular, byproviding a larger diameter of the reactor tube in segment 606 relativeto segments 604 and 608, respectively, one can increase the residencetime of reactants moving through these segments, as the linear velocityof the reactants through such segments decreases, as schematicallyillustrated by the arrows. As will be appreciated, the number and sizevariation of the different segments can be readily varied among reactorsystems in order to achieve the desired results. In particular, areactor may include 2, 3, 4, 5 or more different reactor segments havingvaried cross sectional dimensions to provide different linear flowvelocities.

Again, differing residence times may be employed in catalyzing differentcatalytic reactions, or catalyzing the same reactions under differingconditions. In particular, one may wish to vary residence time of agiven set of reactants over a single catalyst system, in order tocatalyze a reaction more completely, catalyze a different or furtherreaction, or the like. Likewise, different reactors within the systemmay be provided with different catalyst systems which may benefit fromdiffering residence times of the reactants within the catalyst bed tocatalyze the same or different reactions from each other.

Alternatively or additionally, residence times of reactants withincatalyst beds may be configured to optimize thermal control within theoverall reactor system. In particular, residence times may be longer ata zone in the reactor system in which removal of excess thermal energyis less critical or more easily managed, e.g., because the overallreaction has not yet begun generating excessive heat. In contrast, inother zones of the reactor, e.g., where removal of excess thermal energyis more difficult due to rapid exothermic reactivity, the reactorportion may only maintain the reactants for a much shorter time, byproviding a narrower reactor diameter. As will be appreciated, thermalmanagement becomes easier due to the shorter period of time that thereactants are present and reacting to produce heat. Likewise, thereduced volume of a tubular reactor within a reactor housing alsoprovides for a greater volume of cooling media, to more efficientlyremove thermal energy.

In addition to the ethylene conversion processes described herein,components other than ethylene that are produced in an ethyleneproduction process, e.g., contained within an OCM effluent gas, may bedirected to, and thus fluidly connected to additional conversionprocesses in accordance with the invention. In particular, as notedabove, the OCM reaction process generates a number of additionalproducts, other than ethylene, including for example, hydrogen gas (H₂)and carbon monoxide (CO), also referred to as syngas. In accordance withcertain aspects of the invention, the syngas component of the OCMreaction product slate is subjected to additional processing to produceother products and intermediates, e.g., dimethylether (DME), methanol,and hydrocarbons. These components may generally be useful in a varietyof different end products, including liquid fuels, lubricants andpropellants. In an exemplary embodiment, the syngas component of the OCMreaction effluent is separated from the other OCM products. The syngasis then subjected to any of a variety of syngas conversion processes toproduce a variety of different products, e.g., methanol, dimethylether,hydrocarbons, lubricants, waxes and fuels or fuel blendstocks. In oneexample, the syngas component is subjected to a catalytic process toproduce DME via a methanol intermediate. The catalytic process isdescribed in detail in, e.g., U.S. Pat. No. 4,481,305, the fulldisclosure of which is incorporated herein by reference in its entiretyfor all purposes.

EXAMPLES Example 1 Fuel Production from OCM Produced Ethylene

An exemplary liquid fuel production process is shown in FIG. 3 anddescribed in greater detail below.

As shown in FIG. 3, an OCM product gas containing ethylene 302, ispreheated to 200° to 500° C. depending upon the desired process. Theethylene may be from 0.05% to 100% pure. For less than 100% pure, theethylene containing gas may include CO₂, CO, H₂, H₂O, C₂H₆, CH₄, C3 orhigher hydrocarbons (i.e., C3+ hydrocarbons), or combinations thereof.

The heated ethylene containing gas 302 is then flowed through one ormore ethylene conversion reactors, e.g., reactors 304, 306 and 308, eachcontaining a solid acid catalyst. The different reactors may includereactors having the same catalyst for performing a parallel reaction toproduce a single product. Alternatively, and in accordance with certainaspects of the invention, the different reactors may include differentcatalysts and/or be operated under different reaction conditions toproduce different reaction products or product ranges. The catalysts mayinclude crystalline catalysts, such as zeolites, e.g., zeolites ZSM-5,Y, Beta, ZSM-22, ZSM-48, SAPO-34, SAPO-5, SAPO-11, Mordenite,Ferrierite, and others. Alternatively or additionally, the catalysts mayinclude crystalline mesoporous materials, such as SBA-15, SBA-16,MCM-22, MCM-41, and Al-MCM-41 catalysts, among others. Zeolites andmesoporous materials can be modified with metals, metal oxides, or metalions to enhance ethylene reactivity, product slate selectivity, and/orcatalyst stability.

The ethylene reacts with the solid catalyst to make higher carbonoligomers/products (C3-C30). Carbon number ranges can be targeteddepending on catalyst type and process conditions.

The oligomerized ethylene product stream 312 exits from the ethyleneconversion reactor(s) and may be used to heat the incoming ethylenecontaining gas 302, e.g., via a heat exchanger 314. The product streamis otherwise passed through a series of heat exchangers 316, 318, and320 to cool the oligomerized product and to generate steam 322. Theproduct stream 312 is then passed through a flash drum 324 to condenseheavier products into liquids 326 and light products 336 such as C3-C4'sare recycled back to the ethylene conversion reactor in stream 328through compressor 338 for possible reaction if the C3-C4's are olefinicand/or to control the heat of reaction of the ethylene conversionreactors 304, 306 and 308. Alternatively, they may be routed throughdownstream processes, e.g., through hydrogenation reactor 330 in stream336. If desired, the liquid fraction 326 is passed through ahydrogenation reactor 330 to hydrogenate olefins toparaffins/isoparaffins using a Co/Mo, Pd, Ni/Mo or other hydrogenationcatalyst known in the art. The oligomerized product 326 (or optionallyhydrogenated fraction 332) may then be routed to a distillation column334 to fractionate different cuts of products 340, such as gasoline,jet, and diesel fuel, fuel blendstocks or aromatics.

Although described in some detail for purposes of illustration, it willbe readily appreciated that a number of variations known or appreciatedby those of skill in the art may be practiced within the scope ofpresent invention. All terms used herein are intended to have theirordinary meaning unless an alternative definition is expressly providedor is clear from the context used therein. For methods recited herein,to the extent that a composition of the invention is disclosed as beingprovided in a method step, it will be appreciated that disclosure ofsuch provision implicitly discloses the preparation of such compositionin a transformative fashion. To the extent any definition is expresslystated in a patent or publication that is incorporated herein byreference, such definition is expressly disclaimed to the extent that itis in conflict with the ordinary meaning of such terms, unless suchdefinition is specifically and expressly incorporated herein, or it isclear from the context that such definition was intended herein. Unlessotherwise clear from the context or expressly stated, any concentrationvalues provided herein are generally given in terms of admixture valuesor percentages without regard to any conversion that occurs upon orfollowing addition of the particular component of the mixture. To theextent not already expressly incorporated herein, all publishedreferences and patent documents referred to in this disclosure and/orapplication data sheet are incorporated herein by reference in theirentirety for all purposes.

What is claimed is:
 1. A method for producing fuel from ethyleneproduced by oxidative coupling of methane (OCM), the method comprising:(a) providing an OCM product gas comprising ethylene from an OCMprocess; (b) directing a first portion of said OCM product gas into afirst ethylene conversion reactor and directing a second portion of saidOCM product gas into a second ethylene conversion reactor in parallel tosaid first ethylene conversion reactor, said first ethylene conversionreactor and said second ethylene conversion reactor operated underdifferent reactor conditions; (c) in said first ethylene conversionreactor and in said second ethylene conversion reactor, reacting saidethylene from said OCM product gas to produce first higher carbonproducts and second higher carbon products different from said firsthigher carbon products, said first higher carbon products and saidsecond higher carbon products including C₃ to C₁₀ hydrocarbons inseparate streams; (d) combining said separate streams into a productstream, and cooling said product stream in a heat exchanger; (e)directing said product stream from said heat exchanger into a flash drumthat condenses said product stream to produce (i) a light product streamcomprising C₂ to C₄ compounds and (ii) a heavy product stream comprisingC₄ to C₁₀ compounds; (f) directing said light product stream to acompressor that compresses said light product stream; and (g) directingsaid light product stream from said compressor to said first ethyleneconversion reactor or said second ethylene conversion reactor, thereby(i) reacting at least a portion of said C₂ to C₄ compounds from saidlight product stream to produce additional said first higher carbonproducts or second higher carbon products, or (ii) controlling atemperature in said first ethylene conversion reactor or in said secondethylene conversion reactor.
 2. The method of claim 1, wherein saidfirst higher carbon products have a first carbon number range and saidsecond higher carbon products have a second carbon number rangedifferent than said first carbon number range.
 3. The method of claim 1,further comprising fractionating said heavy product stream to produce(i) gasoline, (ii) jet fuel, (iii) diesel fuel, (iv) fuel blendstock, or(v) aromatics.
 4. The method of claim 3, further comprisingfractionating said heavy product stream to produce at least two of(i)-(v).
 5. The method of claim 1, wherein said first ethyleneconversion reactor and said second ethylene conversion reactor eachcomprises a zeolite catalyst.
 6. The method of claim 5, wherein saidzeolite catalyst includes ZSM-5.
 7. The method of claim 5, wherein saidfirst ethylene conversion reactor comprises a different zeolite catalystthan said second ethylene conversion reactor.
 8. The method of claim 1,further comprising directing said heavy product stream into ahydrogenation reactor, and in said hydrogenation reactor hydrogenatingsaid heavy product stream.
 9. The method of claim 8, wherein said heavyproduct stream is hydrogenated with a Co/Mo, Pd, or Ni/Mo hydrogenationcatalyst.
 10. The method of claim 9, wherein olefins in said heavyproduct stream are hydrogenated to paraffins or isoparaffins in saidhydrogenation reactor.
 11. The method of claim 1, wherein said OCMproduct gas comprises between about 0.5% and about 15% ethylene.
 12. Themethod of claim 1, wherein said OCM product gas further comprises CO₂,CO, H₂, H₂O, C₂H₆, CH₄, or C₃₊ hydrocarbons, or any combination thereof.13. The method of claim 1, wherein said OCM product gas furthercomprises propylene.
 14. The method of claim 1, further comprisingcooling said OCM product gas to a temperature between about 200° C. and500° C. prior to (b).
 15. The method of claim 14, further comprisinggenerating steam from said cooling.
 16. The method of claim 1, furthercomprising directing a third portion of said OCM product gas into athird ethylene conversion reactor and in said third ethylene conversionreactor, reacting said ethylene from said OCM product gas to producehigher carbon products including C₃ to C₁₀ compounds.
 17. The method ofclaim 1, wherein each of said first higher carbon products and saidsecond higher carbon products is generated at a selectivity greater thanabout 50%.